diff --git a/browser/brave_browser_process.h b/browser/brave_browser_process.h
index 303ca1a1fb71..206c83be3a40 100644
--- a/browser/brave_browser_process.h
+++ b/browser/brave_browser_process.h
@@ -32,8 +32,6 @@ class LocalDataFilesService;
 
 namespace brave_shields {
 class AdBlockService;
-class AdBlockCustomFiltersService;
-class AdBlockRegionalServiceManager;
 class HTTPSEverywhereService;
 }  // namespace brave_shields
 
@@ -77,10 +75,6 @@ class BraveBrowserProcess {
   virtual ~BraveBrowserProcess();
   virtual void StartBraveServices() = 0;
   virtual brave_shields::AdBlockService* ad_block_service() = 0;
-  virtual brave_shields::AdBlockCustomFiltersService*
-  ad_block_custom_filters_service() = 0;
-  virtual brave_shields::AdBlockRegionalServiceManager*
-  ad_block_regional_service_manager() = 0;
 #if BUILDFLAG(ENABLE_EXTENSIONS)
   virtual brave_component_updater::ExtensionWhitelistService*
   extension_whitelist_service() = 0;
diff --git a/browser/brave_browser_process_impl.cc b/browser/brave_browser_process_impl.cc
index 17761ebcee32..3fdb88ac7983 100644
--- a/browser/brave_browser_process_impl.cc
+++ b/browser/brave_browser_process_impl.cc
@@ -10,6 +10,7 @@
 #include "base/bind.h"
 #include "base/path_service.h"
 #include "base/task/post_task.h"
+#include "base/task/thread_pool.h"
 #include "brave/browser/brave_shields/ad_block_subscription_download_manager_getter.h"
 #include "brave/browser/brave_stats/brave_stats_updater.h"
 #include "brave/browser/component_updater/brave_component_updater_configurator.h"
@@ -23,7 +24,6 @@
 #include "brave/components/brave_component_updater/browser/brave_on_demand_updater.h"
 #include "brave/components/brave_component_updater/browser/local_data_files_service.h"
 #include "brave/components/brave_referrals/buildflags/buildflags.h"
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
 #include "brave/components/brave_shields/browser/ad_block_regional_service_manager.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/ad_block_subscription_service_manager.h"
@@ -192,10 +192,14 @@ void BraveBrowserProcessImpl::StartBraveServices() {
 
 brave_shields::AdBlockService* BraveBrowserProcessImpl::ad_block_service() {
   if (!ad_block_service_) {
+    scoped_refptr<base::SequencedTaskRunner> task_runner(
+        base::ThreadPool::CreateSequencedTaskRunner(
+            {base::MayBlock(), base::TaskPriority::USER_BLOCKING,
+             base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN}));
     ad_block_service_ = std::make_unique<brave_shields::AdBlockService>(
-        brave_component_updater_delegate(),
+        local_state(), GetApplicationLocale(), component_updater(), task_runner,
         std::make_unique<brave_shields::AdBlockSubscriptionServiceManager>(
-            brave_component_updater_delegate(),
+            local_state(), task_runner,
             AdBlockSubscriptionDownloadManagerGetter(),
             profile_manager()->user_data_dir().Append(
                 profile_manager()->GetInitialProfileDir())));
@@ -203,16 +207,6 @@ brave_shields::AdBlockService* BraveBrowserProcessImpl::ad_block_service() {
   return ad_block_service_.get();
 }
 
-brave_shields::AdBlockCustomFiltersService*
-BraveBrowserProcessImpl::ad_block_custom_filters_service() {
-  return ad_block_service()->custom_filters_service();
-}
-
-brave_shields::AdBlockRegionalServiceManager*
-BraveBrowserProcessImpl::ad_block_regional_service_manager() {
-  return ad_block_service()->regional_service_manager();
-}
-
 NTPBackgroundImagesService*
 BraveBrowserProcessImpl::ntp_background_images_service() {
   if (!ntp_background_images_service_) {
@@ -262,9 +256,11 @@ BraveBrowserProcessImpl::debounce_component_installer() {
 
 brave_shields::HTTPSEverywhereService*
 BraveBrowserProcessImpl::https_everywhere_service() {
-  if (!https_everywhere_service_)
+  if (!created_https_everywhere_service_) {
     https_everywhere_service_ = brave_shields::HTTPSEverywhereServiceFactory(
-        brave_component_updater_delegate());
+        brave_component_updater_delegate()->GetTaskRunner());
+    created_https_everywhere_service_ = true;
+  }
   return https_everywhere_service_.get();
 }
 
diff --git a/browser/brave_browser_process_impl.h b/browser/brave_browser_process_impl.h
index 37de5ae0bbf9..65fdeacaaec9 100644
--- a/browser/brave_browser_process_impl.h
+++ b/browser/brave_browser_process_impl.h
@@ -34,8 +34,6 @@ class LocalDataFilesService;
 
 namespace brave_shields {
 class AdBlockService;
-class AdBlockCustomFiltersService;
-class AdBlockRegionalServiceManager;
 class HTTPSEverywhereService;
 }  // namespace brave_shields
 
@@ -90,10 +88,6 @@ class BraveBrowserProcessImpl : public BraveBrowserProcess,
 
   void StartBraveServices() override;
   brave_shields::AdBlockService* ad_block_service() override;
-  brave_shields::AdBlockCustomFiltersService* ad_block_custom_filters_service()
-      override;
-  brave_shields::AdBlockRegionalServiceManager*
-  ad_block_regional_service_manager() override;
 #if BUILDFLAG(ENABLE_EXTENSIONS)
   brave_component_updater::ExtensionWhitelistService*
   extension_whitelist_service() override;
@@ -155,6 +149,7 @@ class BraveBrowserProcessImpl : public BraveBrowserProcess,
 #endif
   std::unique_ptr<debounce::DebounceComponentInstaller>
       debounce_component_installer_;
+  bool created_https_everywhere_service_ = false;
   std::unique_ptr<brave_shields::HTTPSEverywhereService>
       https_everywhere_service_;
   std::unique_ptr<brave_stats::BraveStatsUpdater> brave_stats_updater_;
diff --git a/browser/brave_content_browser_client.cc b/browser/brave_content_browser_client.cc
index 07007ce79124..2809a389e099 100644
--- a/browser/brave_content_browser_client.cc
+++ b/browser/brave_content_browser_client.cc
@@ -876,7 +876,8 @@ BraveContentBrowserClient::CreateThrottlesForNavigation(
           content::NavigationThrottle> domain_block_navigation_throttle =
           brave_shields::DomainBlockNavigationThrottle::MaybeCreateThrottleFor(
               handle, g_brave_browser_process->ad_block_service(),
-              g_brave_browser_process->ad_block_custom_filters_service(),
+              g_brave_browser_process->ad_block_service()
+                  ->custom_filters_provider(),
               EphemeralStorageServiceFactory::GetForContext(context),
               HostContentSettingsMapFactory::GetForProfile(
                   Profile::FromBrowserContext(context)),
diff --git a/browser/brave_shields/ad_block_service_browsertest.cc b/browser/brave_shields/ad_block_service_browsertest.cc
index d89e029646af..c4a3bc642595 100644
--- a/browser/brave_shields/ad_block_service_browsertest.cc
+++ b/browser/brave_shields/ad_block_service_browsertest.cc
@@ -8,6 +8,7 @@
 #include <memory>
 #include <set>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "base/base64.h"
@@ -21,11 +22,11 @@
 #include "brave/common/brave_paths.h"
 #include "brave/common/pref_names.h"
 #include "brave/components/brave_component_updater/browser/local_data_files_service.h"
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
-#include "brave/components/brave_shields/browser/ad_block_regional_service.h"
+#include "brave/components/brave_shields/browser/ad_block_component_installer.h"
+#include "brave/components/brave_shields/browser/ad_block_custom_filters_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_default_filters_provider.h"
 #include "brave/components/brave_shields/browser/ad_block_regional_service_manager.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
-#include "brave/components/brave_shields/browser/ad_block_subscription_service.h"
 #include "brave/components/brave_shields/browser/ad_block_subscription_service_manager.h"
 #include "brave/components/brave_shields/browser/ad_block_subscription_service_manager_observer.h"
 #include "brave/components/brave_shields/browser/brave_shields_util.h"
@@ -38,6 +39,7 @@
 #include "chrome/browser/ui/browser.h"
 #include "chrome/common/chrome_features.h"
 #include "chrome/test/base/ui_test_utils.h"
+#include "components/prefs/pref_change_registrar.h"
 #include "components/prefs/pref_service.h"
 #include "content/public/browser/browser_task_traits.h"
 #include "content/public/test/browser_test.h"
@@ -79,6 +81,12 @@ using brave_shields::features::kBraveAdblockCookieListDefault;
 using brave_shields::features::kBraveAdblockCosmeticFiltering;
 using brave_shields::features::kBraveAdblockDefault1pBlocking;
 
+AdBlockServiceTest::AdBlockServiceTest() {
+  brave_shields::SetDefaultAdBlockComponentIdAndBase64PublicKeyForTest(
+      kDefaultAdBlockComponentTestId, kDefaultAdBlockComponentTest64PublicKey);
+}
+AdBlockServiceTest::~AdBlockServiceTest() {}
+
 void AdBlockServiceTest::SetUpOnMainThread() {
   ExtensionBrowserTest::SetUpOnMainThread();
   host_resolver()->AddRule("*", "127.0.0.1");
@@ -92,7 +100,6 @@ void AdBlockServiceTest::SetUp() {
 void AdBlockServiceTest::PreRunTestOnMainThread() {
   ExtensionBrowserTest::PreRunTestOnMainThread();
   WaitForAdBlockServiceThreads();
-  ASSERT_TRUE(g_brave_browser_process->ad_block_service()->IsInitialized());
 }
 
 HostContentSettingsMap* AdBlockServiceTest::content_settings() {
@@ -102,23 +109,61 @@ HostContentSettingsMap* AdBlockServiceTest::content_settings() {
 void AdBlockServiceTest::UpdateAdBlockInstanceWithRules(
     const std::string& rules,
     const std::string& resources) {
+  auto source_provider =
+      std::make_unique<brave_shields::TestFiltersProvider>(rules, resources);
+
   brave_shields::AdBlockService* ad_block_service =
       g_brave_browser_process->ad_block_service();
-  ad_block_service->GetTaskRunner()->PostTask(
-      FROM_HERE,
-      base::BindOnce(&brave_shields::AdBlockService::ResetForTest,
-                     base::Unretained(ad_block_service), rules, resources));
+  ad_block_service->UseSourceProvidersForTest(source_provider.get(),
+                                              source_provider.get());
+
+  source_providers_.push_back(std::move(source_provider));
+
+  WaitForAdBlockServiceThreads();
+}
+
+void AdBlockServiceTest::UpdateAdBlockInstanceWithDAT(
+    const base::FilePath& dat_location,
+    const std::string& resources) {
+  base::ScopedAllowBlockingForTesting allow_blocking;
+  auto source_provider = std::make_unique<brave_shields::TestFiltersProvider>(
+      dat_location, resources);
+
+  brave_shields::AdBlockService* ad_block_service =
+      g_brave_browser_process->ad_block_service();
+  ad_block_service->UseSourceProvidersForTest(source_provider.get(),
+                                              source_provider.get());
+
+  source_providers_.push_back(std::move(source_provider));
+
+  WaitForAdBlockServiceThreads();
+}
+
+void AdBlockServiceTest::UpdateCustomAdBlockInstanceWithRules(
+    const std::string& rules,
+    const std::string& resources) {
+  auto source_provider =
+      std::make_unique<brave_shields::TestFiltersProvider>(rules, resources);
+
+  brave_shields::AdBlockService* ad_block_service =
+      g_brave_browser_process->ad_block_service();
+  ad_block_service->UseCustomSourceProvidersForTest(source_provider.get(),
+                                                    source_provider.get());
+
+  source_providers_.push_back(std::move(source_provider));
+
   WaitForAdBlockServiceThreads();
 }
 
 void AdBlockServiceTest::AssertTagExists(const std::string& tag,
                                          bool expected_exists) const {
   bool exists_default =
-      g_brave_browser_process->ad_block_service()->TagExists(tag);
+      g_brave_browser_process->ad_block_service()->TagExistsForTest(tag);
   ASSERT_EQ(exists_default, expected_exists);
 
   for (const auto& regional_service :
-       g_brave_browser_process->ad_block_regional_service_manager()
+       g_brave_browser_process->ad_block_service()
+           ->regional_service_manager()
            ->regional_services_) {
     bool exists_regional = regional_service.second->TagExists(tag);
     ASSERT_EQ(exists_regional, expected_exists);
@@ -142,8 +187,6 @@ void AdBlockServiceTest::GetTestDataDir(base::FilePath* test_data_dir) {
 bool AdBlockServiceTest::InstallDefaultAdBlockExtension(
     const std::string& extension_dir,
     int expected_change) {
-  brave_shields::AdBlockService::SetComponentIdAndBase64PublicKeyForTest(
-      kDefaultAdBlockComponentTestId, kDefaultAdBlockComponentTest64PublicKey);
   base::FilePath test_data_dir;
   GetTestDataDir(&test_data_dir);
   const extensions::Extension* ad_block_extension = InstallExtension(
@@ -152,69 +195,91 @@ bool AdBlockServiceTest::InstallDefaultAdBlockExtension(
   if (!ad_block_extension)
     return false;
 
-  g_brave_browser_process->ad_block_service()->OnComponentReady(
-      ad_block_extension->id(), ad_block_extension->path(), "");
+  g_brave_browser_process->ad_block_service()
+      ->default_filters_provider_->OnComponentReady(ad_block_extension->path());
   WaitForAdBlockServiceThreads();
 
   return true;
 }
 
+// A test observer that allows blocking waits for an AdBlockEngine to be
+// updated with new rules.
+class EngineTestObserver : public brave_shields::AdBlockEngine::TestObserver {
+ public:
+  // Constructs an EngineTestObserver which will observe the given adblock
+  // engine for filter data updates.
+  explicit EngineTestObserver(brave_shields::AdBlockEngine* engine)
+      : engine_(engine) {
+    engine_->AddObserverForTest(this);
+  }
+  ~EngineTestObserver() override { engine_->RemoveObserverForTest(); }
+
+  EngineTestObserver(const EngineTestObserver& other) = delete;
+  EngineTestObserver& operator=(const EngineTestObserver& other) = delete;
+
+  // Blocks until the engine is updated
+  void Wait() { run_loop_.Run(); }
+
+ private:
+  void OnEngineUpdated() override { run_loop_.Quit(); }
+
+  base::RunLoop run_loop_;
+  raw_ptr<brave_shields::AdBlockEngine> engine_ = nullptr;
+};
+
 bool AdBlockServiceTest::InstallRegionalAdBlockExtension(
-    const std::string& uuid) {
-  brave_shields::AdBlockRegionalService::
-      SetComponentIdAndBase64PublicKeyForTest(
-          kRegionalAdBlockComponentTestId,
-          kRegionalAdBlockComponentTest64PublicKey);
+    const std::string& uuid,
+    bool enable_list) {
+  // The regional adblock engines depend on the default engine for resource
+  // loads.
+  EXPECT_TRUE(InstallDefaultAdBlockExtension());
+  auto* default_engine =
+      g_brave_browser_process->ad_block_service()->default_service_.get();
+  EngineTestObserver default_engine_observer(default_engine);
+  default_engine_observer.Wait();
+
   base::FilePath test_data_dir;
   GetTestDataDir(&test_data_dir);
   std::vector<adblock::FilterList> regional_catalog;
   regional_catalog.push_back(adblock::FilterList(
       uuid, "https://easylist-downloads.adblockplus.org/liste_fr.txt",
       "EasyList Liste FR", {"fr"}, "https://forums.lanik.us/viewforum.php?f=91",
-      "emaecjinaegfkoklcdafkiocjhoeilao",
-      "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAsbqIWuMS7r2OPXCsIPbbLG1H"
-      "/"
-      "d3NM9uzCMscw7R9ZV3TwhygvMOpZrNp4Y4hImy2H+HE0OniCqzuOAaq7+"
-      "SHXcdHwItvLK"
-      "tnRmeWgdqxgEdzJ8rZMWnfi+dODTbA4QvxI6itU5of8trDFbLzFqgnEOBk8ZxtjM/"
-      "M5v3"
-      "UeYh+EYHSEyHnDSJKbKevlXC931xlbdca0q0Ps3Ln6w/pJFByGbOh212mD/"
-      "PvwS6jIH3L"
-      "YjrMVUMefKC/ywn/AAdnwM5mGirm1NflQCJQOpTjIhbRIXBlACfV/"
-      "hwI1lqfKbFnyr4aP"
-      "Odg3JcOZZVoyi+ko3rKG3vH9JPWEy24Ys9A3SYpTwIDAQAB",
+      kRegionalAdBlockComponentTestId, kRegionalAdBlockComponentTest64PublicKey,
       "Removes advertisements from French websites"));
-  g_brave_browser_process->ad_block_regional_service_manager()
+  g_brave_browser_process->ad_block_service()
+      ->regional_service_manager()
       ->SetRegionalCatalog(regional_catalog);
-  const extensions::Extension* ad_block_extension =
-      InstallExtension(test_data_dir.AppendASCII("adblock-data")
-                           .AppendASCII("adblock-regional")
-                           .AppendASCII(uuid),
-                       1);
-  if (!ad_block_extension)
-    return false;
 
-  g_brave_browser_process->ad_block_regional_service_manager()
-      ->EnableFilterList(uuid, true);
-  EXPECT_EQ(g_brave_browser_process->ad_block_regional_service_manager()
-                ->regional_services_.size(),
-            1ULL);
-
-  auto regional_service =
-      g_brave_browser_process->ad_block_regional_service_manager()
-          ->regional_services_.find(uuid);
-  regional_service->second->OnComponentReady(ad_block_extension->id(),
-                                             ad_block_extension->path(), "");
-  WaitForAdBlockServiceThreads();
-
-  return true;
-}
+  if (enable_list) {
+    const extensions::Extension* ad_block_extension =
+        InstallExtension(test_data_dir.AppendASCII("adblock-data")
+                             .AppendASCII("adblock-regional")
+                             .AppendASCII(uuid),
+                         1);
+    if (!ad_block_extension)
+      return false;
+
+    g_brave_browser_process->ad_block_service()
+        ->regional_service_manager()
+        ->EnableFilterList(uuid, true);
+    EXPECT_EQ(g_brave_browser_process->ad_block_service()
+                  ->regional_service_manager()
+                  ->regional_services_.size(),
+              1ULL);
+
+    auto regional_engine = g_brave_browser_process->ad_block_service()
+                               ->regional_service_manager()
+                               ->regional_services_.find(uuid);
+    EngineTestObserver regional_engine_observer(regional_engine->second.get());
+    auto regional_filters_provider =
+        g_brave_browser_process->ad_block_service()
+            ->regional_service_manager()
+            ->regional_filters_providers_.find(uuid);
+    regional_filters_provider->second->OnComponentReady(
+        ad_block_extension->path());
+    regional_engine_observer.Wait();
+  }
 
-bool AdBlockServiceTest::StartAdBlockRegionalServices() {
-  g_brave_browser_process->ad_block_regional_service_manager()->Start();
-  if (!g_brave_browser_process->ad_block_regional_service_manager()
-           ->IsInitialized())
-    return false;
   return true;
 }
 
@@ -226,34 +291,20 @@ void AdBlockServiceTest::SetSubscriptionIntervals() {
   auto* subscription_service_manager =
       ad_block_service->subscription_service_manager();
 
-  ASSERT_TRUE(ad_block_service->IsInitialized());
-
   subscription_service_manager->SetUpdateIntervalsForTesting(&initial_delay,
                                                              &retry_interval);
 }
 
 void AdBlockServiceTest::WaitForAdBlockServiceThreads() {
   scoped_refptr<base::ThreadTestHelper> tr_helper(new base::ThreadTestHelper(
-      g_brave_browser_process->local_data_files_service()->GetTaskRunner()));
+      g_brave_browser_process->ad_block_service()->GetTaskRunner()));
   ASSERT_TRUE(tr_helper->Run());
 }
 
-void AdBlockServiceTest::WaitForBraveExtensionShieldsDataReady() {
-  // Sometimes, the page can start loading before the Shields panel has
-  // received information about the window and tab it's loaded in.
-  ExtensionTestMessageListener extension_listener(
-      "brave-extension-shields-data-ready", false);
-  ASSERT_TRUE(extension_listener.WaitUntilSatisfied());
-}
-
 void AdBlockServiceTest::ShieldsDown(const GURL& url) {
   brave_shields::SetBraveShieldsEnabled(content_settings(), false, url);
 }
 
-void AdBlockServiceTest::LoadDAT(const base::FilePath path) {
-  g_brave_browser_process->ad_block_service()->GetDATFileData(path);
-}
-
 // Load a page with an ad image, and make sure it is blocked.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, AdsGetBlockedByDefaultBlocker) {
   ASSERT_TRUE(InstallDefaultAdBlockExtension());
@@ -274,8 +325,8 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, AdsGetBlockedByDefaultBlocker) {
 // blocked by custom filters.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
                        NotAdsDoNotGetBlockedByCustomBlocker) {
-  ASSERT_TRUE(g_brave_browser_process->ad_block_custom_filters_service()
-                  ->UpdateCustomFilters("*ad_banner.png"));
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
+  UpdateCustomAdBlockInstanceWithRules("*ad_banner.png");
 
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
 
@@ -293,13 +344,12 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
 // Load a page with an ad image, and make sure it is blocked by custom
 // filters.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, AdsGetBlockedByCustomBlocker) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
 
-  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("");
 
-  ASSERT_TRUE(g_brave_browser_process->ad_block_custom_filters_service()
-                  ->UpdateCustomFilters("*ad_banner.png"));
+  UpdateCustomAdBlockInstanceWithRules("*ad_banner.png");
 
   GURL url = embedded_test_server()->GetURL(kAdBlockTestPage);
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), url));
@@ -315,13 +365,11 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, AdsGetBlockedByCustomBlocker) {
 // Load a page with an ad image, with a corresponding exception installed in
 // the custom filters, and make sure it is not blocked.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, DefaultBlockCustomException) {
-  EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
-
   ASSERT_TRUE(InstallDefaultAdBlockExtension());
+  EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
 
   UpdateAdBlockInstanceWithRules("*ad_banner.png");
-  ASSERT_TRUE(g_brave_browser_process->ad_block_custom_filters_service()
-                  ->UpdateCustomFilters("@@ad_banner.png"));
+  UpdateCustomAdBlockInstanceWithRules("@@ad_banner.png");
 
   GURL url = embedded_test_server()->GetURL(kAdBlockTestPage);
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), url));
@@ -337,10 +385,10 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, DefaultBlockCustomException) {
 // Load a page with an image blocked by custom filters, with a corresponding
 // exception installed in the default filters, and make sure it is not blocked.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CustomBlockDefaultException) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   UpdateAdBlockInstanceWithRules("@@ad_banner.png");
-  ASSERT_TRUE(g_brave_browser_process->ad_block_custom_filters_service()
-                  ->UpdateCustomFilters("*ad_banner.png"));
+  UpdateCustomAdBlockInstanceWithRules("*ad_banner.png");
 
   GURL url = embedded_test_server()->GetURL(kAdBlockTestPage);
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), url));
@@ -380,7 +428,6 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, AdsGetBlockedByRegionalBlocker) {
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
 
   ASSERT_TRUE(InstallRegionalAdBlockExtension(kAdBlockEasyListFranceUUID));
-  ASSERT_TRUE(StartAdBlockRegionalServices());
 
   GURL url = embedded_test_server()->GetURL(kAdBlockTestPage);
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), url));
@@ -403,7 +450,6 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
 
   ASSERT_TRUE(InstallRegionalAdBlockExtension(kAdBlockEasyListFranceUUID));
-  ASSERT_TRUE(StartAdBlockRegionalServices());
 
   GURL url = embedded_test_server()->GetURL(kAdBlockTestPage);
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), url));
@@ -580,6 +626,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, SubFrameShieldsOff) {
 
 // Requests made by a service worker should be blocked as well.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, ServiceWorkerRequest) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("adbanner.js");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
 
@@ -601,14 +648,13 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, ServiceWorkerRequest) {
 // the start it adds an exception rule to the non regional adblocker.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
                        ExceptionAdsAreAllowedAcrossClients) {
-  UpdateAdBlockInstanceWithRules("*ad_fr*\n@@*ad_fr.png*");
   g_browser_process->SetApplicationLocale("fr");
   ASSERT_STREQ(g_browser_process->GetApplicationLocale().c_str(), "fr");
 
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
 
   ASSERT_TRUE(InstallRegionalAdBlockExtension(kAdBlockEasyListFranceUUID));
-  ASSERT_TRUE(StartAdBlockRegionalServices());
+  UpdateAdBlockInstanceWithRules("*ad_fr*\n@@*ad_fr.png*");
 
   GURL url = embedded_test_server()->GetURL(kAdBlockTestPage);
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), url));
@@ -622,6 +668,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
 
 // Make sure the third-party flag is passed into the ad-block library properly
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, AdBlockThirdPartyWorksByETLDP1) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("||a.com$third-party");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
 
@@ -641,6 +688,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, AdBlockThirdPartyWorksByETLDP1) {
 // Make sure the third-party flag is passed into the ad-block library properly
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
                        AdBlockThirdPartyWorksForThirdPartyHost) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("||a.com$third-party");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   GURL tab_url = embedded_test_server()->GetURL("b.com", kAdBlockTestPage);
@@ -716,6 +764,7 @@ class TestAdBlockSubscriptionServiceManagerObserver
 // although it doesn't seem to occur in real usage.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
                        MAYBE_SubscribeToCustomSubscription) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   GURL subscription_url =
       embedded_test_server()->GetURL("lists.com", "/list.txt");
@@ -819,6 +868,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
 
 // Make sure the state of a list that cannot be fetched is as expected
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, SubscribeTo404List) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   GURL subscription_url =
       embedded_test_server()->GetURL("lists.com", "/this/list/does/not/exist");
@@ -863,6 +913,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, SubscribeTo404List) {
 
 // Make sure that a list cannot be subscribed to twice
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, SubscribeToListUrlTwice) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   GURL subscription_url =
       embedded_test_server()->GetURL("lists.com", "/this/list/does/not/exist");
@@ -905,6 +956,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, SubscribeToListUrlTwice) {
 // issue the correct number of DNS resolutions
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
                        MAYBE_CnameCloakedRequestsGetBlocked) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("||cname-cloak-endpoint.tracking.com^");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   GURL tab_url = embedded_test_server()->GetURL("a.com", kAdBlockTestPage);
@@ -990,6 +1042,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
 // to its CNAME-uncloaked equivalent.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
                        MAYBE_CnameCloakedRequestsCanBeExcepted) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules(
       "||cname-cloak-endpoint.tracking.com^\n"
       "@@||a.com/logo-unblock.png|");
@@ -1086,6 +1139,7 @@ class CnameUncloakingFlagDisabledTest : public AdBlockServiceTest {
 // Make sure that CNAME uncloaking does not occur when the CNAME uncloaking
 // flag is disabled.
 IN_PROC_BROWSER_TEST_F(CnameUncloakingFlagDisabledTest, NoDnsQueriesIssued) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("||cname-cloak-endpoint.tracking.com^");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   GURL tab_url = embedded_test_server()->GetURL("a.com", kAdBlockTestPage);
@@ -1167,6 +1221,7 @@ IN_PROC_BROWSER_TEST_F(CnameUncloakingFlagDisabledTest, NoDnsQueriesIssued) {
 
 // Load an image from a specific subdomain, and make sure it is blocked.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, BlockNYP) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("||sp1.nypost.com$third-party");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   GURL tab_url = embedded_test_server()->GetURL("b.com", kAdBlockTestPage);
@@ -1184,6 +1239,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, BlockNYP) {
 
 // Frame root URL is used for context rather than the tab URL
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, FrameSourceURL) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("adbanner.js$domain=a.com");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   GURL url = embedded_test_server()->GetURL("a.com", "/iframe_blocking.html");
@@ -1208,6 +1264,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, FrameSourceURL) {
 
 // Tags for social buttons work
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, SocialButttonAdBlockTagTest) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules(
       base::StringPrintf("||example.com^$tag=%s",
                          brave_shields::kFacebookEmbeds)
@@ -1231,6 +1288,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, SocialButttonAdBlockTagTest) {
 
 // Lack of tags for social buttons work
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, SocialButttonAdBlockDiffTagTest) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("||example.com^$tag=sup");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   GURL tab_url = embedded_test_server()->GetURL("b.com", kAdBlockTestPage);
@@ -1251,6 +1309,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, SocialButttonAdBlockDiffTagTest) {
 
 // Tags are preserved after resetting
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, ResetPreservesTags) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   g_brave_browser_process->ad_block_service()->EnableTag(
       brave_shields::kFacebookEmbeds, true);
   WaitForAdBlockServiceThreads();
@@ -1420,6 +1479,7 @@ class Default1pBlockingFlagDisabledTest : public AdBlockServiceTest {
 // match the same filter in the default engine. Ensure the third-party one is
 // blocked while the first-party one is allowed.
 IN_PROC_BROWSER_TEST_F(Default1pBlockingFlagDisabledTest, Default1pBlocking) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   UpdateAdBlockInstanceWithRules("^ad_banner.png");
 
@@ -1444,6 +1504,7 @@ IN_PROC_BROWSER_TEST_F(Default1pBlockingFlagDisabledTest, Default1pBlocking) {
 // ensure that both are blocked.
 IN_PROC_BROWSER_TEST_F(Default1pBlockingFlagDisabledTest,
                        Aggressive1pBlocking) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
   brave_shields::SetCosmeticFilteringControlType(
       content_settings(), brave_shields::ControlType::BLOCK, GURL());
@@ -1469,9 +1530,9 @@ IN_PROC_BROWSER_TEST_F(Default1pBlockingFlagDisabledTest,
 // match the same filter in the custom filters engine. Ensure that both are
 // blocked.
 IN_PROC_BROWSER_TEST_F(Default1pBlockingFlagDisabledTest, Custom1pBlocking) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
-  ASSERT_TRUE(g_brave_browser_process->ad_block_custom_filters_service()
-                  ->UpdateCustomFilters("^ad_banner.png"));
+  UpdateCustomAdBlockInstanceWithRules("^ad_banner.png");
   WaitForAdBlockServiceThreads();
 
   GURL url = embedded_test_server()->GetURL(kAdBlockTestPage);
@@ -1492,6 +1553,7 @@ IN_PROC_BROWSER_TEST_F(Default1pBlockingFlagDisabledTest, Custom1pBlocking) {
 
 // Load a page with a script which uses a redirect data URL.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, RedirectRulesAreRespected) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("js_mock_me.js$redirect=noopjs",
                                  R"(
       [
@@ -1526,6 +1588,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, RedirectRulesAreRespected) {
 // A redirection should only be applied if there's also a matching blocking
 // rule.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, RedirectWithoutBlockIsNoop) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   // The DAT for this test contains the following rules:
   //   .js?block=true
   //   js_mock_me.js$redirect-rule=noopjs
@@ -1534,16 +1597,19 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, RedirectWithoutBlockIsNoop) {
   // packager eventually begins shipping DATs that include them.
   base::FilePath test_data_dir;
   GetTestDataDir(&test_data_dir);
-  LoadDAT(test_data_dir.AppendASCII("adblock-data")
-              .AppendASCII("redirect-rule.dat"));
-  g_brave_browser_process->ad_block_service()->AddResources(R"([{
+
+  base::FilePath dat_location = test_data_dir.AppendASCII("adblock-data")
+                                    .AppendASCII("redirect-rule.dat");
+  std::string resources = R"([{
         "name": "noop.js",
         "aliases": ["noopjs"],
         "kind": {
           "mime":"application/javascript"
         },
         "content": "KGZ1bmN0aW9uKCkgewogICAgJ3VzZSBzdHJpY3QnOwp9KSgpOwo="
-      }])");
+      }])";
+  UpdateAdBlockInstanceWithDAT(dat_location, resources);
+
   WaitForAdBlockServiceThreads();
 
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
@@ -1578,6 +1644,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, RedirectWithoutBlockIsNoop) {
 // Verify that scripts violating a Content Security Policy from a `$csp` rule
 // are not loaded.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CspRule) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules(
       "||example.com^$csp=script-src 'nonce-abcdef' 'unsafe-eval' 'self'");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
@@ -1606,13 +1673,13 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CspRule) {
 // The policy resulting from two of the same kind of directive will be the
 // union of both.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CspRuleMerging) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules(
       "||example.com^$csp=script-src 'nonce-abcdef' 'unsafe-eval' 'self'");
-  ASSERT_TRUE(g_brave_browser_process->ad_block_custom_filters_service()
-                  ->UpdateCustomFilters(
-                      "||example.com^$csp=img-src 'none'\n"
-                      "||sub.example.com^$csp=script-src 'nonce-abcdef' "
-                      "'unsafe-eval' 'unsafe-inline'"));
+  UpdateCustomAdBlockInstanceWithRules(
+      "||example.com^$csp=img-src 'none'\n"
+      "||sub.example.com^$csp=script-src 'nonce-abcdef' "
+      "'unsafe-eval' 'unsafe-inline'");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
 
   const GURL url =
@@ -1636,6 +1703,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CspRuleMerging) {
 // Verify that scripts violating a Content Security Policy from a `$csp` rule
 // are not loaded.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CspRuleShieldsDown) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules(
       "||example.com^$csp=script-src 'nonce-abcdef' 'unsafe-eval' 'self'");
   EXPECT_EQ(browser()->profile()->GetPrefs()->GetUint64(kAdsBlocked), 0ULL);
@@ -1672,10 +1740,10 @@ class CosmeticFilteringFlagDisabledTest : public AdBlockServiceTest {
 // Ensure no cosmetic filtering occurs when the feature flag is disabled
 IN_PROC_BROWSER_TEST_F(CosmeticFilteringFlagDisabledTest,
                        CosmeticFilteringSimple) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules(
       "b.com###ad-banner\n"
       "##.ad");
-  WaitForBraveExtensionShieldsDataReady();
 
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
@@ -1695,14 +1763,13 @@ IN_PROC_BROWSER_TEST_F(CosmeticFilteringFlagDisabledTest,
 
 // Ensure no cosmetic filtering occurs when the shields setting is disabled
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringDisabled) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   brave_shields::SetCosmeticFilteringControlType(
       content_settings(), brave_shields::ControlType::ALLOW, GURL());
   UpdateAdBlockInstanceWithRules(
       "b.com###ad-banner\n"
       "##.ad");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -1721,12 +1788,11 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringDisabled) {
 
 // Test simple cosmetic filtering
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringSimple) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules(
       "b.com###ad-banner\n"
       "##.ad");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -1776,6 +1842,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringSimple) {
 
 // Test cosmetic filtering ignores content determined to be 1st party
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringProtect1p) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules(
       "appspot.com##.fpsponsored\n"
       "appspot.com##.fpsponsored1\n"
@@ -1783,8 +1850,6 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringProtect1p) {
       "appspot.com##.fpsponsored3\n"
       "appspot.com##.fpsponsored4\n");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   // *.appspot.com is used here to check the eTLD logic.
   // It's a private suffix from https://publicsuffix.org/list/
   GURL tab_url = embedded_test_server()->GetURL("test.lion.appspot.com",
@@ -1811,12 +1876,11 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringProtect1p) {
 
 // Test cosmetic filtering bypasses 1st party checks when toggled
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringHide1pContent) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   brave_shields::SetCosmeticFilteringControlType(
       content_settings(), brave_shields::ControlType::BLOCK, GURL());
   UpdateAdBlockInstanceWithRules("b.com##.fpsponsored\n");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -1840,10 +1904,9 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringHide1pContent) {
 
 // Test cosmetic filtering on elements added dynamically
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringDynamic) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("##.blockme");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -1882,11 +1945,11 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringDynamic) {
 // Test cosmetic filtering on elements added dynamically, using a rule from the
 // custom filters
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringDynamicCustom) {
-  ASSERT_TRUE(g_brave_browser_process->ad_block_custom_filters_service()
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
+  ASSERT_TRUE(g_brave_browser_process->ad_block_service()
+                  ->custom_filters_provider()
                   ->UpdateCustomFilters("##.blockme"));
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -1926,13 +1989,12 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringDynamicCustom) {
 // `generichide` exception rule, both for elements added dynamically and
 // elements present at page load
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringGenerichide) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules(
       "##.blockme\n"
       "##img[src=\"https://example.com/logo.png\"]\n"
       "@@||b.com$generichide");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -1952,10 +2014,9 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringGenerichide) {
 
 // Test custom style rules
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringCustomStyle) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("b.com##.ad:style(padding-bottom: 10px)");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -1979,14 +2040,13 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringCustomStyle) {
 
 // Test rules overridden by hostname-specific exception rules
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringUnhide) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules(
       "##.ad\n"
       "b.com#@#.ad\n"
       "###ad-banner\n"
       "a.com#@##ad-banner");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -2023,6 +2083,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringUnhide) {
 
 // Test scriptlet injection that modifies window attributes
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringWindowScriptlet) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   /* "content" below corresponds to the following scriptlet:
    * ```
    * (function() {
@@ -2044,8 +2105,6 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringWindowScriptlet) {
       "uKHNlbGVjdG9yKSB7CiAgICByZXR1cm4geyAnY29sb3InOiAnSW1wb3NzaWJsZSB2YW"
       "x1ZScgfTsKICB9Cn0pKCk7Cg==\"}]");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -2069,6 +2128,7 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringWindowScriptlet) {
 
 // Test scriptlet injection that modifies window attributes
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringIframeScriptlet) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   std::string scriptlet =
       "(function() {"
       "  window.JSON.parse = function() { return {} }"
@@ -2084,8 +2144,6 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringIframeScriptlet) {
       "\"content\": \"" +
           scriptlet_base64 + "\"}]");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/iframe_messenger.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -2100,10 +2158,9 @@ IN_PROC_BROWSER_TEST_F(AdBlockServiceTest, CosmeticFilteringIframeScriptlet) {
 // marker on its `display` style.
 IN_PROC_BROWSER_TEST_F(AdBlockServiceTest,
                        CosmeticFilteringOverridesImportant) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
   UpdateAdBlockInstanceWithRules("###inline-block-important");
 
-  WaitForBraveExtensionShieldsDataReady();
-
   GURL tab_url =
       embedded_test_server()->GetURL("b.com", "/cosmetic_filtering.html");
   ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), tab_url));
@@ -2135,36 +2192,40 @@ class DefaultCookieListFlagEnabledTest : public AdBlockServiceTest {
   base::test::ScopedFeatureList feature_list_;
 };
 
+class CookieListPrefObserver {
+ public:
+  explicit CookieListPrefObserver(PrefService* local_state) {
+    pref_change_registrar_.Init(local_state);
+    pref_change_registrar_.Add(
+        brave_shields::prefs::kAdBlockRegionalFilters,
+        base::BindRepeating(&CookieListPrefObserver::OnUpdated,
+                            base::Unretained(this)));
+  }
+  ~CookieListPrefObserver() {}
+
+  CookieListPrefObserver(const CookieListPrefObserver& other) = delete;
+  CookieListPrefObserver& operator=(const CookieListPrefObserver& other) =
+      delete;
+
+  void Wait() { run_loop_.Run(); }
+
+ private:
+  void OnUpdated() { run_loop_.Quit(); }
+
+  base::RunLoop run_loop_;
+  PrefChangeRegistrar pref_change_registrar_;
+};
+
 // Test that the `brave-adblock-default-1p-blocking` flag forces the Cookie
 // List UUID to be enabled, until manually enabled and then disabled again.
-IN_PROC_BROWSER_TEST_F(DefaultCookieListFlagEnabledTest,
-                       CosmeticFilteringIframeScriptlet) {
-  std::vector<adblock::FilterList> regional_catalog =
-      std::vector<adblock::FilterList>();
-  regional_catalog.push_back(adblock::FilterList(
-      brave_shields::kCookieListUuid,
-      "https://easylist-downloads.adblockplus.org/liste_fr.txt",
-      "EasyList Liste FR", {"fr"}, "https://forums.lanik.us/viewforum.php?f=91",
-      "emaecjinaegfkoklcdafkiocjhoeilao",
-      "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAsbqIWuMS7r2OPXCsIPbbLG1H"
-      "/"
-      "d3NM9uzCMscw7R9ZV3TwhygvMOpZrNp4Y4hImy2H+HE0OniCqzuOAaq7+"
-      "SHXcdHwItvLK"
-      "tnRmeWgdqxgEdzJ8rZMWnfi+dODTbA4QvxI6itU5of8trDFbLzFqgnEOBk8ZxtjM/"
-      "M5v3"
-      "UeYh+EYHSEyHnDSJKbKevlXC931xlbdca0q0Ps3Ln6w/pJFByGbOh212mD/"
-      "PvwS6jIH3L"
-      "YjrMVUMefKC/ywn/AAdnwM5mGirm1NflQCJQOpTjIhbRIXBlACfV/"
-      "hwI1lqfKbFnyr4aP"
-      "Odg3JcOZZVoyi+ko3rKG3vH9JPWEy24Ys9A3SYpTwIDAQAB",
-      "Removes advertisements from French websites"));
-  g_brave_browser_process->ad_block_regional_service_manager()
-      ->SetRegionalCatalog(regional_catalog);
+IN_PROC_BROWSER_TEST_F(DefaultCookieListFlagEnabledTest, ListEnabled) {
+  ASSERT_TRUE(
+      InstallRegionalAdBlockExtension(brave_shields::kCookieListUuid, false));
 
   {
-    const auto lists =
-        g_brave_browser_process->ad_block_regional_service_manager()
-            ->GetRegionalLists();
+    const auto lists = g_brave_browser_process->ad_block_service()
+                           ->regional_service_manager()
+                           ->GetRegionalLists();
     // Although never explicitly enabled, it should be presented as enabled by
     // default at first.
     ASSERT_EQ(1UL, lists->GetList().size());
@@ -2172,17 +2233,25 @@ IN_PROC_BROWSER_TEST_F(DefaultCookieListFlagEnabledTest,
   }
 
   // Enable the filter list, and then disable it again.
-  g_brave_browser_process->ad_block_regional_service_manager()
-      ->EnableFilterList(brave_shields::kCookieListUuid, true);
-  g_brave_browser_process->ad_block_regional_service_manager()
-      ->EnableFilterList(brave_shields::kCookieListUuid, false);
-
-  WaitForBraveExtensionShieldsDataReady();
+  {
+    g_brave_browser_process->ad_block_service()
+        ->regional_service_manager()
+        ->EnableFilterList(brave_shields::kCookieListUuid, true);
+    CookieListPrefObserver pref_observer(g_browser_process->local_state());
+    pref_observer.Wait();
+  }
+  {
+    g_brave_browser_process->ad_block_service()
+        ->regional_service_manager()
+        ->EnableFilterList(brave_shields::kCookieListUuid, false);
+    CookieListPrefObserver pref_observer(g_browser_process->local_state());
+    pref_observer.Wait();
+  }
 
   {
-    const auto lists =
-        g_brave_browser_process->ad_block_regional_service_manager()
-            ->GetRegionalLists();
+    const auto lists = g_brave_browser_process->ad_block_service()
+                           ->regional_service_manager()
+                           ->GetRegionalLists();
     // It should be actually disabled now.
     ASSERT_EQ(1UL, lists->GetList().size());
     EXPECT_EQ(false, lists->GetList()[0].FindKey("enabled")->GetBool());
diff --git a/browser/brave_shields/ad_block_service_browsertest.h b/browser/brave_shields/ad_block_service_browsertest.h
index 1a2e48c0ff02..187f08ce44ea 100644
--- a/browser/brave_shields/ad_block_service_browsertest.h
+++ b/browser/brave_shields/ad_block_service_browsertest.h
@@ -6,16 +6,24 @@
 #ifndef BRAVE_BROWSER_BRAVE_SHIELDS_AD_BLOCK_SERVICE_BROWSERTEST_H_
 #define BRAVE_BROWSER_BRAVE_SHIELDS_AD_BLOCK_SERVICE_BROWSERTEST_H_
 
+#include <memory>
 #include <string>
+#include <vector>
 
+#include "brave/components/brave_shields/browser/test_filters_provider.h"
 #include "chrome/browser/extensions/extension_browsertest.h"
 #include "content/public/test/content_mock_cert_verifier.h"
 
 class HostContentSettingsMap;
 
+namespace brave_shields {
+class AdBlockService;
+}  // namespace brave_shields
+
 class AdBlockServiceTest : public extensions::ExtensionBrowserTest {
  public:
-  AdBlockServiceTest() {}
+  AdBlockServiceTest();
+  ~AdBlockServiceTest() override;
 
   // ExtensionBrowserTest overrides
   void SetUpOnMainThread() override;
@@ -27,7 +35,12 @@ class AdBlockServiceTest : public extensions::ExtensionBrowserTest {
 
   HostContentSettingsMap* content_settings();
   void UpdateAdBlockInstanceWithRules(const std::string& rules,
-                                      const std::string& resources = "");
+                                      const std::string& resources = "[]");
+  void UpdateAdBlockInstanceWithDAT(const base::FilePath& dat_location,
+                                    const std::string& resources = "[]");
+  void UpdateCustomAdBlockInstanceWithRules(
+      const std::string& rules,
+      const std::string& resources = "[]");
   void AssertTagExists(const std::string& tag, bool expected_exists) const;
   void InitEmbeddedTestServer();
   void GetTestDataDir(base::FilePath* test_data_dir);
@@ -36,13 +49,16 @@ class AdBlockServiceTest : public extensions::ExtensionBrowserTest {
   bool InstallDefaultAdBlockExtension(
       const std::string& extension_dir = "adblock-default",
       int expected_change = 1);
-  bool InstallRegionalAdBlockExtension(const std::string& uuid);
-  bool StartAdBlockRegionalServices();
+  bool InstallRegionalAdBlockExtension(const std::string& uuid,
+                                       bool enable_list = true);
   void SetSubscriptionIntervals();
   void WaitForAdBlockServiceThreads();
-  void WaitForBraveExtensionShieldsDataReady();
   void ShieldsDown(const GURL& url);
   void LoadDAT(base::FilePath path);
+  void EnableRedirectUrlParsing();
+
+  std::vector<std::unique_ptr<brave_shields::TestFiltersProvider>>
+      source_providers_;
 };
 
 #endif  // BRAVE_BROWSER_BRAVE_SHIELDS_AD_BLOCK_SERVICE_BROWSERTEST_H_
diff --git a/browser/brave_shields/domain_block_page_browsertest.cc b/browser/brave_shields/domain_block_page_browsertest.cc
index 3a952757492b..5cdc15351a05 100644
--- a/browser/brave_shields/domain_block_page_browsertest.cc
+++ b/browser/brave_shields/domain_block_page_browsertest.cc
@@ -8,7 +8,8 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/bind.h"
 #include "brave/browser/brave_browser_process.h"
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
+#include "brave/components/brave_shields/browser/ad_block_custom_filters_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/brave_shields_util.h"
 #include "brave/components/brave_shields/common/features.h"
 #include "chrome/browser/extensions/extension_browsertest.h"
@@ -318,7 +319,8 @@ IN_PROC_BROWSER_TEST_F(DomainBlockTest, NoFetch) {
 
 IN_PROC_BROWSER_TEST_F(DomainBlockTest, NoThirdPartyInterstitial) {
   ASSERT_TRUE(InstallDefaultAdBlockExtension());
-  ASSERT_TRUE(g_brave_browser_process->ad_block_custom_filters_service()
+  ASSERT_TRUE(g_brave_browser_process->ad_block_service()
+                  ->custom_filters_provider()
                   ->UpdateCustomFilters("||b.com^$third-party"));
 
   GURL url = embedded_test_server()->GetURL("a.com", "/simple_link.html");
diff --git a/browser/brave_shields/https_everywhere_component_installer.cc b/browser/brave_shields/https_everywhere_component_installer.cc
new file mode 100644
index 000000000000..65d7b096c900
--- /dev/null
+++ b/browser/brave_shields/https_everywhere_component_installer.cc
@@ -0,0 +1,184 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "brave/browser/brave_shields/https_everywhere_component_installer.h"
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "base/base64.h"
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/no_destructor.h"
+#include "brave/browser/brave_browser_process.h"
+#include "brave/components/brave_component_updater/browser/brave_on_demand_updater.h"
+#include "brave/components/brave_shields/browser/https_everywhere_service.h"
+#include "chrome/browser/browser_process.h"
+#include "components/component_updater/component_installer.h"
+#include "components/component_updater/component_updater_service.h"
+#include "crypto/sha2.h"
+
+using brave_component_updater::BraveOnDemandUpdater;
+
+namespace brave_shields {
+
+namespace {
+
+constexpr size_t kHashSize = 32;
+const char kHTTPSEverywhereComponentName[] = "Brave HTTPS Everywhere Updater";
+const char kHTTPSEverywhereComponentId[] = "oofiananboodjbbmdelgdommihjbkfag";
+const char kHTTPSEverywhereComponentBase64PublicKey[] =
+    "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvn9zSMjTmhkQyrZu5UdN"
+    "350nPqLoSeCYngcC7yDFwaUHjoBQXCZqGeDC69ciCQ2mlRhcV2nxXqlUDkiC6+7m"
+    "651nI+gi4oVqHagc7EFUyGA0yuIk7qIMvCBdH7wbET27de0rzbRzRht9EKzEjIhC"
+    "BtoPnmyrO/8qPrH4XR4cPfnFPuJssBBxC1B35H7rh0Br9qePhPDDe9OjyqYxPuio"
+    "+YcC9obL4g5krVrfrlKLfFNpIewUcJyBpSlCgfxEyEhgDkK9cILTMUi5vC7GxS3P"
+    "OtZqgfRg8Da4i+NwmjQqrz0JFtPMMSyUnmeMj+mSOL4xZVWr8fU2/GOCXs9gczDp"
+    "JwIDAQAB";
+
+class HTTPSEverywhereComponentInstallerPolicy
+    : public component_updater::ComponentInstallerPolicy {
+ public:
+  HTTPSEverywhereComponentInstallerPolicy();
+  ~HTTPSEverywhereComponentInstallerPolicy() override;
+
+  HTTPSEverywhereComponentInstallerPolicy(
+      const HTTPSEverywhereComponentInstallerPolicy&) = delete;
+  HTTPSEverywhereComponentInstallerPolicy& operator=(
+      const HTTPSEverywhereComponentInstallerPolicy&) = delete;
+
+  // component_updater::ComponentInstallerPolicy
+  bool SupportsGroupPolicyEnabledComponentUpdates() const override;
+  bool RequiresNetworkEncryption() const override;
+  update_client::CrxInstaller::Result OnCustomInstall(
+      const base::Value& manifest,
+      const base::FilePath& install_dir) override;
+  void OnCustomUninstall() override;
+  bool VerifyInstallation(const base::Value& manifest,
+                          const base::FilePath& install_dir) const override;
+  void ComponentReady(const base::Version& version,
+                      const base::FilePath& path,
+                      base::Value manifest) override;
+  base::FilePath GetRelativeInstallDir() const override;
+  void GetHash(std::vector<uint8_t>* hash) const override;
+  std::string GetName() const override;
+  update_client::InstallerAttributes GetInstallerAttributes() const override;
+
+  static base::NoDestructor<std::string> g_https_everywhere_component_id_;
+  static base::NoDestructor<std::string>
+      g_https_everywhere_component_base64_public_key_;
+
+ private:
+  const std::string component_id_;
+  const std::string component_name_;
+  uint8_t component_hash_[kHashSize];
+};
+
+base::NoDestructor<std::string>
+    HTTPSEverywhereComponentInstallerPolicy::g_https_everywhere_component_id_(
+        kHTTPSEverywhereComponentId);
+base::NoDestructor<std::string> HTTPSEverywhereComponentInstallerPolicy::
+    g_https_everywhere_component_base64_public_key_(
+        kHTTPSEverywhereComponentBase64PublicKey);
+
+HTTPSEverywhereComponentInstallerPolicy::
+    HTTPSEverywhereComponentInstallerPolicy()
+    : component_id_(kHTTPSEverywhereComponentId),
+      component_name_(kHTTPSEverywhereComponentName) {
+  // Generate hash from public key.
+  std::string decoded_public_key;
+  base::Base64Decode(kHTTPSEverywhereComponentBase64PublicKey,
+                     &decoded_public_key);
+  crypto::SHA256HashString(decoded_public_key, component_hash_, kHashSize);
+}
+
+HTTPSEverywhereComponentInstallerPolicy::
+    ~HTTPSEverywhereComponentInstallerPolicy() = default;
+
+bool HTTPSEverywhereComponentInstallerPolicy::
+    SupportsGroupPolicyEnabledComponentUpdates() const {
+  return true;
+}
+
+bool HTTPSEverywhereComponentInstallerPolicy::RequiresNetworkEncryption()
+    const {
+  return false;
+}
+
+update_client::CrxInstaller::Result
+HTTPSEverywhereComponentInstallerPolicy::OnCustomInstall(
+    const base::Value& manifest,
+    const base::FilePath& install_dir) {
+  return update_client::CrxInstaller::Result(0);
+}
+
+void HTTPSEverywhereComponentInstallerPolicy::OnCustomUninstall() {}
+
+void HTTPSEverywhereComponentInstallerPolicy::ComponentReady(
+    const base::Version& version,
+    const base::FilePath& path,
+    base::Value manifest) {
+  if (g_browser_process->IsShuttingDown())
+    return;
+
+  g_brave_browser_process->https_everywhere_service()->InitDB(path);
+}
+
+bool HTTPSEverywhereComponentInstallerPolicy::VerifyInstallation(
+    const base::Value& manifest,
+    const base::FilePath& install_dir) const {
+  return true;
+}
+
+base::FilePath HTTPSEverywhereComponentInstallerPolicy::GetRelativeInstallDir()
+    const {
+  return base::FilePath::FromUTF8Unsafe(component_id_);
+}
+
+void HTTPSEverywhereComponentInstallerPolicy::GetHash(
+    std::vector<uint8_t>* hash) const {
+  hash->assign(component_hash_, component_hash_ + kHashSize);
+}
+
+std::string HTTPSEverywhereComponentInstallerPolicy::GetName() const {
+  return component_name_;
+}
+
+update_client::InstallerAttributes
+HTTPSEverywhereComponentInstallerPolicy::GetInstallerAttributes() const {
+  return update_client::InstallerAttributes();
+}
+
+void OnRegistered() {
+  BraveOnDemandUpdater::GetInstance()->OnDemandUpdate(
+      kHTTPSEverywhereComponentId);
+}
+
+}  // namespace
+
+// static
+void SetHTTPSEverywhereComponentIdAndBase64PublicKeyForTest(
+    const std::string& component_id,
+    const std::string& component_base64_public_key) {
+  *HTTPSEverywhereComponentInstallerPolicy::g_https_everywhere_component_id_ =
+      component_id;
+  *HTTPSEverywhereComponentInstallerPolicy::
+      g_https_everywhere_component_base64_public_key_ =
+      component_base64_public_key;
+}
+
+void RegisterHTTPSEverywhereComponent(
+    component_updater::ComponentUpdateService* cus) {
+  // In test, |cus| could be nullptr.
+  if (!cus)
+    return;
+
+  auto installer = base::MakeRefCounted<component_updater::ComponentInstaller>(
+      std::make_unique<HTTPSEverywhereComponentInstallerPolicy>());
+  installer->Register(cus, base::BindOnce(&OnRegistered));
+}
+
+}  // namespace brave_shields
diff --git a/browser/brave_shields/https_everywhere_component_installer.h b/browser/brave_shields/https_everywhere_component_installer.h
new file mode 100644
index 000000000000..fd9c471342b1
--- /dev/null
+++ b/browser/brave_shields/https_everywhere_component_installer.h
@@ -0,0 +1,26 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_BROWSER_BRAVE_SHIELDS_HTTPS_EVERYWHERE_COMPONENT_INSTALLER_H_
+#define BRAVE_BROWSER_BRAVE_SHIELDS_HTTPS_EVERYWHERE_COMPONENT_INSTALLER_H_
+
+#include <string>
+
+namespace component_updater {
+class ComponentUpdateService;
+}  // namespace component_updater
+
+namespace brave_shields {
+
+void SetHTTPSEverywhereComponentIdAndBase64PublicKeyForTest(
+    const std::string& component_id,
+    const std::string& component_base64_public_key);
+
+void RegisterHTTPSEverywhereComponent(
+    component_updater::ComponentUpdateService* cus);
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_BROWSER_BRAVE_SHIELDS_HTTPS_EVERYWHERE_COMPONENT_INSTALLER_H_
diff --git a/browser/brave_shields/sources.gni b/browser/brave_shields/sources.gni
index 7f095d304c07..67d0def2f896 100644
--- a/browser/brave_shields/sources.gni
+++ b/browser/brave_shields/sources.gni
@@ -14,6 +14,8 @@ brave_browser_brave_shields_sources = [
   "//brave/browser/brave_shields/brave_shields_web_contents_observer.h",
   "//brave/browser/brave_shields/cookie_pref_service_factory.cc",
   "//brave/browser/brave_shields/cookie_pref_service_factory.h",
+  "//brave/browser/brave_shields/https_everywhere_component_installer.cc",
+  "//brave/browser/brave_shields/https_everywhere_component_installer.h",
 ]
 
 brave_browser_brave_shields_deps = [
diff --git a/browser/ephemeral_storage/ephemeral_storage_1p_domain_block_browsertest.cc b/browser/ephemeral_storage/ephemeral_storage_1p_domain_block_browsertest.cc
index ea899c2f9b75..7b4f24d8ee1d 100644
--- a/browser/ephemeral_storage/ephemeral_storage_1p_domain_block_browsertest.cc
+++ b/browser/ephemeral_storage/ephemeral_storage_1p_domain_block_browsertest.cc
@@ -12,6 +12,7 @@
 #include "brave/components/brave_component_updater/browser/local_data_files_service.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/brave_shields_util.h"
+#include "brave/components/brave_shields/browser/test_filters_provider.h"
 #include "brave/components/brave_shields/common/features.h"
 #include "chrome/browser/interstitials/security_interstitial_page_test_utils.h"
 #include "chrome/browser/profiles/profile.h"
@@ -45,12 +46,13 @@ class EphemeralStorage1pDomainBlockBrowserTest
 
   void UpdateAdBlockInstanceWithRules(const std::string& rules,
                                       const std::string& resources = "") {
+    source_provider_ =
+        std::make_unique<brave_shields::TestFiltersProvider>(rules, resources);
+
     brave_shields::AdBlockService* ad_block_service =
         g_brave_browser_process->ad_block_service();
-    ad_block_service->GetTaskRunner()->PostTask(
-        FROM_HERE,
-        base::BindOnce(&brave_shields::AdBlockService::ResetForTest,
-                       base::Unretained(ad_block_service), rules, resources));
+    ad_block_service->UseSourceProvidersForTest(source_provider_.get(),
+                                                source_provider_.get());
     WaitForAdBlockServiceThreads();
   }
 
@@ -160,6 +162,7 @@ class EphemeralStorage1pDomainBlockBrowserTest
   }
 
  protected:
+  std::unique_ptr<brave_shields::TestFiltersProvider> source_provider_;
   base::test::ScopedFeatureList scoped_feature_list_;
   GURL a_site_simple_url_;
   GURL b_site_simple_url_;
diff --git a/browser/extensions/api/brave_shields_api.cc b/browser/extensions/api/brave_shields_api.cc
index cf7000f6f466..f4238d19e45a 100644
--- a/browser/extensions/api/brave_shields_api.cc
+++ b/browser/extensions/api/brave_shields_api.cc
@@ -14,7 +14,7 @@
 #include "brave/browser/ui/brave_pages.h"
 #include "brave/browser/webcompat_reporter/webcompat_reporter_dialog.h"
 #include "brave/common/extensions/api/brave_shields.h"
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
+#include "brave/components/brave_shields/browser/ad_block_custom_filters_provider.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/brave_shields_p3a.h"
 #include "brave/components/brave_shields/browser/brave_shields_util.h"
@@ -51,12 +51,12 @@ BraveShieldsAddSiteCosmeticFilterFunction::Run() {
       brave_shields::AddSiteCosmeticFilter::Params::Create(args()));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
-  auto* custom_filters_service =
-      g_brave_browser_process->ad_block_custom_filters_service();
-  std::string custom_filters = custom_filters_service->GetCustomFilters();
-  custom_filters_service->UpdateCustomFilters(custom_filters + '\n' +
-                                              params->host + "##" +
-                                              params->css_selector + '\n');
+  auto* custom_filters_provider =
+      g_brave_browser_process->ad_block_service()->custom_filters_provider();
+  std::string custom_filters = custom_filters_provider->GetCustomFilters();
+  custom_filters_provider->UpdateCustomFilters(custom_filters + '\n' +
+                                               params->host + "##" +
+                                               params->css_selector + '\n');
 
   return RespondNow(NoArguments());
 }
diff --git a/browser/net/brave_ad_block_csp_network_delegate_helper.cc b/browser/net/brave_ad_block_csp_network_delegate_helper.cc
index 1b26e19f7245..160723243838 100644
--- a/browser/net/brave_ad_block_csp_network_delegate_helper.cc
+++ b/browser/net/brave_ad_block_csp_network_delegate_helper.cc
@@ -77,9 +77,6 @@ int OnHeadersReceived_AdBlockCspWork(
           new net::HttpResponseHeaders(response_headers->raw_headers());
     }
 
-    scoped_refptr<base::SequencedTaskRunner> task_runner =
-        g_brave_browser_process->ad_block_service()->GetTaskRunner();
-
     std::string original_csp_string;
     absl::optional<std::string> original_csp = absl::nullopt;
     if ((*override_response_headers)
@@ -90,11 +87,13 @@ int OnHeadersReceived_AdBlockCspWork(
 
     (*override_response_headers)->RemoveHeader("Content-Security-Policy");
 
-    task_runner->PostTaskAndReplyWithResult(
-        FROM_HERE,
-        base::BindOnce(&GetCspDirectivesOnTaskRunner, ctx, original_csp),
-        base::BindOnce(&OnReceiveCspDirectives, next_callback, ctx,
-                       *override_response_headers));
+    g_brave_browser_process->ad_block_service()
+        ->GetTaskRunner()
+        ->PostTaskAndReplyWithResult(
+            FROM_HERE,
+            base::BindOnce(&GetCspDirectivesOnTaskRunner, ctx, original_csp),
+            base::BindOnce(&OnReceiveCspDirectives, next_callback, ctx,
+                           *override_response_headers));
     return net::ERR_IO_PENDING;
   }
 
diff --git a/browser/net/brave_ad_block_tp_network_delegate_helper_unittest.cc b/browser/net/brave_ad_block_tp_network_delegate_helper_unittest.cc
index 9c158cef99f8..f0a21b60647d 100644
--- a/browser/net/brave_ad_block_tp_network_delegate_helper_unittest.cc
+++ b/browser/net/brave_ad_block_tp_network_delegate_helper_unittest.cc
@@ -18,6 +18,7 @@
 #include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/ad_block_subscription_download_manager.h"
 #include "brave/components/brave_shields/browser/ad_block_subscription_service_manager.h"
+#include "brave/components/brave_shields/browser/test_filters_provider.h"
 #include "brave/test/base/testing_brave_browser_process.h"
 #include "chrome/browser/net/system_network_context_manager.h"
 #include "chrome/common/chrome_paths.h"
@@ -31,6 +32,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 using brave::ResponseCallback;
+using brave_shields::TestFiltersProvider;
 
 namespace {
 
@@ -95,9 +97,12 @@ class BraveAdBlockTPNetworkDelegateHelperTest : public testing::Test {
     base::FilePath user_data_dir;
     DCHECK(base::PathService::Get(chrome::DIR_USER_DATA, &user_data_dir));
     auto adblock_service = std::make_unique<brave_shields::AdBlockService>(
-        brave_component_updater_delegate_.get(),
+        brave_component_updater_delegate_->local_state(),
+        brave_component_updater_delegate_->locale(), nullptr,
+        brave_component_updater_delegate_->GetTaskRunner(),
         std::make_unique<brave_shields::AdBlockSubscriptionServiceManager>(
-            brave_component_updater_delegate_.get(),
+            brave_component_updater_delegate_->local_state(),
+            brave_component_updater_delegate_->GetTaskRunner(),
             base::BindOnce(&FakeAdBlockSubscriptionDownloadManagerGetter),
             user_data_dir));
 
@@ -123,10 +128,10 @@ class BraveAdBlockTPNetworkDelegateHelperTest : public testing::Test {
     TestingBraveBrowserProcess::DeleteInstance();
   }
 
-  void ResetAdblockInstance(brave_shields::AdBlockBaseService* service,
-                            std::string rules,
-                            std::string resources) {
-    service->ResetForTest(rules, resources);
+  void ResetAdblockInstance(std::string rules, std::string resources) {
+    filters_provider_ = std::make_unique<TestFiltersProvider>(rules, resources);
+    g_brave_browser_process->ad_block_service()->UseSourceProvidersForTest(
+        filters_provider_.get(), filters_provider_.get());
   }
 
   // Returns true if the request handler deferred control back to the calling
@@ -154,6 +159,8 @@ class BraveAdBlockTPNetworkDelegateHelperTest : public testing::Test {
 
   std::unique_ptr<StubResolverConfigReader> stub_resolver_config_reader_;
 
+  std::unique_ptr<TestFiltersProvider> filters_provider_;
+
  private:
   std::unique_ptr<network::HostResolver> resolver_wrapper_;
 };
@@ -204,8 +211,7 @@ TEST_F(BraveAdBlockTPNetworkDelegateHelperTest, RequestDataURL) {
 }
 
 TEST_F(BraveAdBlockTPNetworkDelegateHelperTest, SimpleBlocking) {
-  ResetAdblockInstance(g_brave_browser_process->ad_block_service(),
-                       "||brave.com/test.txt", "");
+  ResetAdblockInstance("||brave.com/test.txt", "");
 
   const GURL url("https://brave.com/test.txt");
   auto request_info = std::make_shared<brave::BraveRequestInfo>(url);
diff --git a/browser/net/brave_httpse_network_delegate_helper.cc b/browser/net/brave_httpse_network_delegate_helper.cc
index 2a5a7b7ed6f8..ca81d4baaabf 100644
--- a/browser/net/brave_httpse_network_delegate_helper.cc
+++ b/browser/net/brave_httpse_network_delegate_helper.cc
@@ -23,12 +23,15 @@ using content::BrowserThread;
 
 namespace brave {
 
-void OnBeforeURLRequest_HttpseFileWork(std::shared_ptr<BraveRequestInfo> ctx) {
+void OnBeforeURLRequest_HttpseFileWork(
+    base::WeakPtr<brave_shields::HTTPSEverywhereService::Engine> engine,
+    std::shared_ptr<BraveRequestInfo> ctx) {
   base::ScopedBlockingCall scoped_blocking_call(FROM_HERE,
                                                 base::BlockingType::WILL_BLOCK);
   DCHECK_NE(ctx->request_identifier, 0U);
-  g_brave_browser_process->https_everywhere_service()->GetHTTPSURL(
-      &ctx->request_url, ctx->request_identifier, &ctx->new_url_spec);
+  if (engine)
+    engine->GetHTTPSURL(&ctx->request_url, ctx->request_identifier,
+                        &ctx->new_url_spec);
 }
 
 void OnBeforeURLRequest_HttpsePostFileWork(
@@ -79,7 +82,11 @@ int OnBeforeURLRequest_HttpsePreFileWork(
       g_brave_browser_process->https_everywhere_service()
           ->GetTaskRunner()
           ->PostTaskAndReply(
-              FROM_HERE, base::BindOnce(OnBeforeURLRequest_HttpseFileWork, ctx),
+              FROM_HERE,
+              base::BindOnce(
+                  OnBeforeURLRequest_HttpseFileWork,
+                  g_brave_browser_process->https_everywhere_service()->engine(),
+                  ctx),
               base::BindOnce(
                   base::IgnoreResult(&OnBeforeURLRequest_HttpsePostFileWork),
                   next_callback, ctx));
diff --git a/browser/ui/webui/brave_adblock_ui.cc b/browser/ui/webui/brave_adblock_ui.cc
index ba46fbd4e1b7..479ab59867a1 100644
--- a/browser/ui/webui/brave_adblock_ui.cc
+++ b/browser/ui/webui/brave_adblock_ui.cc
@@ -14,7 +14,7 @@
 #include "brave/browser/ui/webui/brave_webui_source.h"
 #include "brave/common/webui_url_constants.h"
 #include "brave/components/brave_adblock/resources/grit/brave_adblock_generated_map.h"
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
+#include "brave/components/brave_shields/browser/ad_block_custom_filters_provider.h"
 #include "brave/components/brave_shields/browser/ad_block_regional_service_manager.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/ad_block_service_helper.h"
@@ -143,7 +143,8 @@ void AdblockDOMHandler::HandleEnableFilterList(
 
   std::string uuid = args[0].GetString();
   bool enabled = args[1].GetBool();
-  g_brave_browser_process->ad_block_regional_service_manager()
+  g_brave_browser_process->ad_block_service()
+      ->regional_service_manager()
       ->EnableFilterList(uuid, enabled);
 }
 
@@ -151,9 +152,9 @@ void AdblockDOMHandler::HandleGetCustomFilters(
     base::Value::ConstListView args) {
   DCHECK_EQ(args.size(), 0U);
   AllowJavascript();
-  const std::string custom_filters =
-      g_brave_browser_process->ad_block_custom_filters_service()
-          ->GetCustomFilters();
+  const std::string custom_filters = g_brave_browser_process->ad_block_service()
+                                         ->custom_filters_provider()
+                                         ->GetCustomFilters();
   CallJavascriptFunction("brave_adblock.onGetCustomFilters",
                          base::Value(custom_filters));
 }
@@ -163,7 +164,8 @@ void AdblockDOMHandler::HandleGetRegionalLists(
   DCHECK_EQ(args.size(), 0U);
   AllowJavascript();
   std::unique_ptr<base::ListValue> regional_lists =
-      g_brave_browser_process->ad_block_regional_service_manager()
+      g_brave_browser_process->ad_block_service()
+          ->regional_service_manager()
           ->GetRegionalLists();
   CallJavascriptFunction("brave_adblock.onGetRegionalLists", *regional_lists);
 }
@@ -182,7 +184,8 @@ void AdblockDOMHandler::HandleUpdateCustomFilters(
     return;
 
   std::string custom_filters = args[0].GetString();
-  g_brave_browser_process->ad_block_custom_filters_service()
+  g_brave_browser_process->ad_block_service()
+      ->custom_filters_provider()
       ->UpdateCustomFilters(custom_filters);
 }
 
diff --git a/chromium_src/chrome/browser/component_updater/registration.cc b/chromium_src/chrome/browser/component_updater/registration.cc
index a0a5dbdc9cc6..e902949440bf 100644
--- a/chromium_src/chrome/browser/component_updater/registration.cc
+++ b/chromium_src/chrome/browser/component_updater/registration.cc
@@ -9,8 +9,9 @@
 #include "src/chrome/browser/component_updater/registration.cc"
 #undef RegisterComponentsForUpdate
 
-#include "chrome/browser/browser_process.h"
+#include "brave/browser/brave_shields/https_everywhere_component_installer.h"
 #include "brave/components/brave_wallet/browser/wallet_data_files_installer.h"
+#include "chrome/browser/browser_process.h"
 
 namespace component_updater {
 
@@ -18,6 +19,7 @@ void RegisterComponentsForUpdate() {
   RegisterComponentsForUpdate_ChromiumImpl();
   ComponentUpdateService* cus = g_browser_process->component_updater();
   brave_wallet::RegisterWalletDataFilesComponent(cus);
+  brave_shields::RegisterHTTPSEverywhereComponent(cus);
 }
 
 }  // namespace component_updater
diff --git a/components/brave_component_updater/browser/dat_file_util.cc b/components/brave_component_updater/browser/dat_file_util.cc
index ea142ea3212b..9376d9db8850 100644
--- a/components/brave_component_updater/browser/dat_file_util.cc
+++ b/components/brave_component_updater/browser/dat_file_util.cc
@@ -5,16 +5,17 @@
 
 #include "brave/components/brave_component_updater/browser/dat_file_util.h"
 
+#include <memory>
 #include <string>
 
 #include "base/logging.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 
-namespace brave_component_updater {
+namespace {
 
 void GetDATFileData(const base::FilePath& file_path,
-                    DATFileDataBuffer* buffer) {
+                    brave_component_updater::DATFileDataBuffer* buffer) {
   int64_t size = 0;
   if (!base::PathExists(file_path) ||
       !base::GetFileSize(file_path, &size) ||
@@ -34,6 +35,16 @@ void GetDATFileData(const base::FilePath& file_path,
   }
 }
 
+}  // namespace
+
+namespace brave_component_updater {
+
+DATFileDataBuffer ReadDATFileData(const base::FilePath& dat_file_path) {
+  DATFileDataBuffer buffer;
+  GetDATFileData(dat_file_path, &buffer);
+  return buffer;
+}
+
 std::string GetDATFileAsString(const base::FilePath& file_path) {
   std::string contents;
   bool success = base::ReadFileToString(file_path, &contents);
diff --git a/components/brave_component_updater/browser/dat_file_util.h b/components/brave_component_updater/browser/dat_file_util.h
index 2c0a2c7c8700..164ae9b8ce66 100644
--- a/components/brave_component_updater/browser/dat_file_util.h
+++ b/components/brave_component_updater/browser/dat_file_util.h
@@ -17,17 +17,17 @@ namespace brave_component_updater {
 
 using DATFileDataBuffer = std::vector<unsigned char>;
 
-void GetDATFileData(const base::FilePath& file_path, DATFileDataBuffer* buffer);
 std::string GetDATFileAsString(const base::FilePath& file_path);
 
+DATFileDataBuffer ReadDATFileData(const base::FilePath& dat_file_path);
+
 template <typename T>
 using LoadDATFileDataResult =
     std::pair<std::unique_ptr<T>, brave_component_updater::DATFileDataBuffer>;
 
 template <typename T>
 LoadDATFileDataResult<T> LoadDATFileData(const base::FilePath& dat_file_path) {
-  DATFileDataBuffer buffer;
-  GetDATFileData(dat_file_path, &buffer);
+  DATFileDataBuffer buffer = ReadDATFileData(dat_file_path);
   std::unique_ptr<T> client;
   client = std::make_unique<T>();
   if (buffer.empty() ||
@@ -39,8 +39,7 @@ LoadDATFileDataResult<T> LoadDATFileData(const base::FilePath& dat_file_path) {
 
 template <typename T>
 LoadDATFileDataResult<T> LoadRawFileData(const base::FilePath& dat_file_path) {
-  DATFileDataBuffer buffer;
-  GetDATFileData(dat_file_path, &buffer);
+  DATFileDataBuffer buffer = ReadDATFileData(dat_file_path);
   std::unique_ptr<T> client;
 
   if (!buffer.empty())
diff --git a/components/brave_extension/extension/brave_extension/background/reducers/shieldsPanelReducer.ts b/components/brave_extension/extension/brave_extension/background/reducers/shieldsPanelReducer.ts
index 9e7f70b95068..4dcf26b952cf 100644
--- a/components/brave_extension/extension/brave_extension/background/reducers/shieldsPanelReducer.ts
+++ b/components/brave_extension/extension/brave_extension/background/reducers/shieldsPanelReducer.ts
@@ -108,9 +108,6 @@ export default function shieldsPanelReducer (
       // and used interchangably and all this code will be removed soon.
       state = shieldsPanelState.updateTabShieldsData(state, action.details.id, action.details)
       shieldsPanelState.updateShieldsIcon(state)
-      if (chrome.test && shieldsPanelState.getActiveTabData(state)) {
-        chrome.test.sendMessage('brave-extension-shields-data-ready')
-      }
       break
     }
     case shieldsPanelTypes.SHIELDS_TOGGLED: {
diff --git a/components/brave_perf_predictor/browser/perf_predictor_tab_helper_browsertest.cc b/components/brave_perf_predictor/browser/perf_predictor_tab_helper_browsertest.cc
index 8c3bf6a4f0bf..be18323f629f 100644
--- a/components/brave_perf_predictor/browser/perf_predictor_tab_helper_browsertest.cc
+++ b/components/brave_perf_predictor/browser/perf_predictor_tab_helper_browsertest.cc
@@ -11,8 +11,8 @@
 #include "brave/common/pref_names.h"
 #include "brave/components/brave_component_updater/browser/local_data_files_service.h"
 #include "brave/components/brave_perf_predictor/common/pref_names.h"
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
+#include "brave/components/brave_shields/browser/test_filters_provider.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/test/base/in_process_browser_test.h"
@@ -39,6 +39,8 @@ uint64_t getProfileAdsBlocked(Browser* browser) {
 
 }  // namespace
 
+using brave_shields::TestFiltersProvider;
+
 class PerfPredictorTabHelperTest : public InProcessBrowserTest {
  public:
   PerfPredictorTabHelperTest() {}
@@ -55,8 +57,6 @@ class PerfPredictorTabHelperTest : public InProcessBrowserTest {
 
   void PreRunTestOnMainThread() override {
     InProcessBrowserTest::PreRunTestOnMainThread();
-    // Need ad_block_service to be available to get blocking savings predictions
-    ASSERT_TRUE(g_brave_browser_process->ad_block_service()->IsInitialized());
   }
 
   void TearDown() override { InProcessBrowserTest::TearDown(); }
@@ -71,21 +71,24 @@ class PerfPredictorTabHelperTest : public InProcessBrowserTest {
   }
 
   void UpdateAdBlockInstanceWithRules(const std::string& rules) {
+    filters_provider_ = std::make_unique<TestFiltersProvider>(rules, "");
+
     brave_shields::AdBlockService* ad_block_service =
         g_brave_browser_process->ad_block_service();
-    ad_block_service->GetTaskRunner()->PostTask(
-        FROM_HERE,
-        base::BindOnce(&brave_shields::AdBlockService::ResetForTest,
-                       base::Unretained(ad_block_service), rules, ""));
+
+    ad_block_service->UseSourceProvidersForTest(filters_provider_.get(),
+                                                filters_provider_.get());
 
     WaitForAdBlockServiceThreads();
   }
 
   void WaitForAdBlockServiceThreads() {
     scoped_refptr<base::ThreadTestHelper> tr_helper(new base::ThreadTestHelper(
-        g_brave_browser_process->local_data_files_service()->GetTaskRunner()));
+        g_brave_browser_process->ad_block_service()->GetTaskRunner()));
     ASSERT_TRUE(tr_helper->Run());
   }
+
+  std::unique_ptr<TestFiltersProvider> filters_provider_;
 };
 
 IN_PROC_BROWSER_TEST_F(PerfPredictorTabHelperTest, NoBlockNoSavings) {
diff --git a/components/brave_shields/browser/BUILD.gn b/components/brave_shields/browser/BUILD.gn
index 9b82030b27f6..3ce8bbdf90bd 100644
--- a/components/brave_shields/browser/BUILD.gn
+++ b/components/brave_shields/browser/BUILD.gn
@@ -1,15 +1,25 @@
 static_library("browser") {
   sources = [
-    "ad_block_base_service.cc",
-    "ad_block_base_service.h",
-    "ad_block_custom_filters_service.cc",
-    "ad_block_custom_filters_service.h",
+    "ad_block_component_installer.cc",
+    "ad_block_component_installer.h",
+    "ad_block_custom_filters_provider.cc",
+    "ad_block_custom_filters_provider.h",
+    "ad_block_default_filters_provider.cc",
+    "ad_block_default_filters_provider.h",
+    "ad_block_engine.cc",
+    "ad_block_engine.h",
+    "ad_block_filters_provider.cc",
+    "ad_block_filters_provider.h",
     "ad_block_pref_service.cc",
     "ad_block_pref_service.h",
-    "ad_block_regional_service.cc",
-    "ad_block_regional_service.h",
+    "ad_block_regional_catalog_provider.cc",
+    "ad_block_regional_catalog_provider.h",
+    "ad_block_regional_filters_provider.cc",
+    "ad_block_regional_filters_provider.h",
     "ad_block_regional_service_manager.cc",
     "ad_block_regional_service_manager.h",
+    "ad_block_resource_provider.cc",
+    "ad_block_resource_provider.h",
     "ad_block_service.cc",
     "ad_block_service.h",
     "ad_block_service_helper.cc",
@@ -18,8 +28,8 @@ static_library("browser") {
     "ad_block_subscription_download_client.h",
     "ad_block_subscription_download_manager.cc",
     "ad_block_subscription_download_manager.h",
-    "ad_block_subscription_service.cc",
-    "ad_block_subscription_service.h",
+    "ad_block_subscription_filters_provider.cc",
+    "ad_block_subscription_filters_provider.h",
     "ad_block_subscription_service_manager.cc",
     "ad_block_subscription_service_manager.h",
     "ad_block_subscription_service_manager_observer.h",
diff --git a/components/brave_shields/browser/ad_block_component_installer.cc b/components/brave_shields/browser/ad_block_component_installer.cc
new file mode 100644
index 000000000000..1fa9359d8f6d
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_component_installer.cc
@@ -0,0 +1,190 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "brave/components/brave_shields/browser/ad_block_component_installer.h"
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "base/base64.h"
+#include "base/bind.h"
+#include "base/callback.h"
+#include "brave/components/brave_component_updater/browser/brave_on_demand_updater.h"
+#include "components/component_updater/component_installer.h"
+#include "components/component_updater/component_updater_service.h"
+#include "crypto/sha2.h"
+
+using brave_component_updater::BraveOnDemandUpdater;
+
+namespace brave_shields {
+
+namespace {
+
+constexpr size_t kHashSize = 32;
+const char kAdBlockComponentName[] = "Brave Ad Block Updater";
+const char kAdBlockComponentId[] = "cffkpbalmllkdoenhmdmpbkajipdjfam";
+const char kAdBlockComponentBase64PublicKey[] =
+    "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAs0qzJmHSgIiw7IGFCxij"
+    "1NnB5hJ5ZQ1LKW9htL4EBOaMJvmqaDs/wfq0nw/goBHWsqqkMBynRTu2Hxxirvdb"
+    "cugn1Goys5QKPgAvKwDHJp9jlnADWm5xQvPQ4GE1mK1/I3ka9cEOCzPW6GI+wGLi"
+    "VPx9VZrxHHsSBIJRaEB5Tyi5bj0CZ+kcfMnRTsXIBw3C6xJgCVKISQUkd8mawVvG"
+    "vqOhBOogCdb9qza5eJ1Cgx8RWKucFfaWWxKLOelCiBMT1Hm1znAoVBHG/blhJJOD"
+    "5HcH/heRrB4MvrE1J76WF3fvZ03aHVcnlLtQeiNNOZ7VbBDXdie8Nomf/QswbBGa"
+    "VwIDAQAB";
+
+std::string g_ad_block_component_id_(kAdBlockComponentId);
+std::string g_ad_block_component_base64_public_key_(
+    kAdBlockComponentBase64PublicKey);
+
+class AdBlockComponentInstallerPolicy
+    : public component_updater::ComponentInstallerPolicy {
+ public:
+  explicit AdBlockComponentInstallerPolicy(
+      const std::string& component_public_key,
+      const std::string& component_id,
+      const std::string& component_name,
+      OnComponentReadyCallback callback);
+  ~AdBlockComponentInstallerPolicy() override;
+
+  AdBlockComponentInstallerPolicy(const AdBlockComponentInstallerPolicy&) =
+      delete;
+  AdBlockComponentInstallerPolicy& operator=(
+      const AdBlockComponentInstallerPolicy&) = delete;
+
+  // component_updater::ComponentInstallerPolicy
+  bool SupportsGroupPolicyEnabledComponentUpdates() const override;
+  bool RequiresNetworkEncryption() const override;
+  update_client::CrxInstaller::Result OnCustomInstall(
+      const base::Value& manifest,
+      const base::FilePath& install_dir) override;
+  void OnCustomUninstall() override;
+  bool VerifyInstallation(const base::Value& manifest,
+                          const base::FilePath& install_dir) const override;
+  void ComponentReady(const base::Version& version,
+                      const base::FilePath& path,
+                      base::Value manifest) override;
+  base::FilePath GetRelativeInstallDir() const override;
+  void GetHash(std::vector<uint8_t>* hash) const override;
+  std::string GetName() const override;
+  update_client::InstallerAttributes GetInstallerAttributes() const override;
+
+ private:
+  const std::string component_id_;
+  const std::string component_name_;
+  OnComponentReadyCallback ready_callback_;
+  uint8_t component_hash_[kHashSize];
+};
+
+AdBlockComponentInstallerPolicy::AdBlockComponentInstallerPolicy(
+    const std::string& component_public_key,
+    const std::string& component_id,
+    const std::string& component_name,
+    OnComponentReadyCallback callback)
+    : component_id_(component_id),
+      component_name_(component_name),
+      ready_callback_(callback) {
+  // Generate hash from public key.
+  std::string decoded_public_key;
+  base::Base64Decode(component_public_key, &decoded_public_key);
+  crypto::SHA256HashString(decoded_public_key, component_hash_, kHashSize);
+}
+
+AdBlockComponentInstallerPolicy::~AdBlockComponentInstallerPolicy() = default;
+
+bool AdBlockComponentInstallerPolicy::
+    SupportsGroupPolicyEnabledComponentUpdates() const {
+  return true;
+}
+
+bool AdBlockComponentInstallerPolicy::RequiresNetworkEncryption() const {
+  return false;
+}
+
+update_client::CrxInstaller::Result
+AdBlockComponentInstallerPolicy::OnCustomInstall(
+    const base::Value& manifest,
+    const base::FilePath& install_dir) {
+  return update_client::CrxInstaller::Result(0);
+}
+
+void AdBlockComponentInstallerPolicy::OnCustomUninstall() {}
+
+void AdBlockComponentInstallerPolicy::ComponentReady(
+    const base::Version& version,
+    const base::FilePath& path,
+    base::Value manifest) {
+  ready_callback_.Run(path);
+}
+
+bool AdBlockComponentInstallerPolicy::VerifyInstallation(
+    const base::Value& manifest,
+    const base::FilePath& install_dir) const {
+  return true;
+}
+
+base::FilePath AdBlockComponentInstallerPolicy::GetRelativeInstallDir() const {
+  return base::FilePath::FromUTF8Unsafe(component_id_);
+}
+
+void AdBlockComponentInstallerPolicy::GetHash(
+    std::vector<uint8_t>* hash) const {
+  hash->assign(component_hash_, component_hash_ + kHashSize);
+}
+
+std::string AdBlockComponentInstallerPolicy::GetName() const {
+  return component_name_;
+}
+
+update_client::InstallerAttributes
+AdBlockComponentInstallerPolicy::GetInstallerAttributes() const {
+  return update_client::InstallerAttributes();
+}
+
+void OnRegistered(const std::string& component_id) {
+  BraveOnDemandUpdater::GetInstance()->OnDemandUpdate(component_id);
+}
+
+}  // namespace
+
+void RegisterAdBlockDefaultComponent(
+    component_updater::ComponentUpdateService* cus,
+    OnComponentReadyCallback callback) {
+  // In test, |cus| could be nullptr.
+  if (!cus)
+    return;
+
+  auto installer = base::MakeRefCounted<component_updater::ComponentInstaller>(
+      std::make_unique<AdBlockComponentInstallerPolicy>(
+          g_ad_block_component_base64_public_key_, g_ad_block_component_id_,
+          kAdBlockComponentName, callback));
+  installer->Register(cus, base::BindOnce(&OnRegistered, kAdBlockComponentId));
+}
+
+void RegisterAdBlockRegionalComponent(
+    component_updater::ComponentUpdateService* cus,
+    const std::string& component_public_key,
+    const std::string& component_id,
+    const std::string& component_name,
+    OnComponentReadyCallback callback) {
+  // In test, |cus| could be nullptr.
+  if (!cus)
+    return;
+
+  auto installer = base::MakeRefCounted<component_updater::ComponentInstaller>(
+      std::make_unique<AdBlockComponentInstallerPolicy>(
+          component_public_key, component_id, component_name, callback));
+  installer->Register(cus, base::BindOnce(&OnRegistered, component_id));
+}
+
+// static
+void SetDefaultAdBlockComponentIdAndBase64PublicKeyForTest(
+    const std::string& component_id,
+    const std::string& component_base64_public_key) {
+  g_ad_block_component_id_ = component_id;
+  g_ad_block_component_base64_public_key_ = component_base64_public_key;
+}
+
+}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_component_installer.h b/components/brave_shields/browser/ad_block_component_installer.h
new file mode 100644
index 000000000000..3e3c578cdd5d
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_component_installer.h
@@ -0,0 +1,41 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_COMPONENT_INSTALLER_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_COMPONENT_INSTALLER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
+
+namespace component_updater {
+class ComponentUpdateService;
+}  // namespace component_updater
+
+namespace brave_shields {
+
+// static
+void SetDefaultAdBlockComponentIdAndBase64PublicKeyForTest(
+    const std::string& component_id,
+    const std::string& component_base64_public_key);
+
+using OnComponentReadyCallback =
+    base::RepeatingCallback<void(const base::FilePath& install_path)>;
+
+void RegisterAdBlockDefaultComponent(
+    component_updater::ComponentUpdateService* cus,
+    OnComponentReadyCallback callback);
+
+void RegisterAdBlockRegionalComponent(
+    component_updater::ComponentUpdateService* cus,
+    const std::string& component_public_key,
+    const std::string& component_id,
+    const std::string& component_name,
+    OnComponentReadyCallback callback);
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_COMPONENT_INSTALLER_H_
diff --git a/components/brave_shields/browser/ad_block_custom_filters_provider.cc b/components/brave_shields/browser/ad_block_custom_filters_provider.cc
new file mode 100644
index 000000000000..020aeb8ce8fd
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_custom_filters_provider.cc
@@ -0,0 +1,58 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "brave/components/brave_shields/browser/ad_block_custom_filters_provider.h"
+
+#include <utility>
+#include <vector>
+
+#include "base/threading/thread_task_runner_handle.h"
+#include "brave/components/brave_shields/common/pref_names.h"
+#include "components/prefs/pref_service.h"
+
+namespace brave_shields {
+
+AdBlockCustomFiltersProvider::AdBlockCustomFiltersProvider(
+    PrefService* local_state)
+    : local_state_(local_state) {}
+
+AdBlockCustomFiltersProvider::~AdBlockCustomFiltersProvider() {}
+
+std::string AdBlockCustomFiltersProvider::GetCustomFilters() {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  if (!local_state_)
+    return std::string();
+  return local_state_->GetString(prefs::kAdBlockCustomFilters);
+}
+
+bool AdBlockCustomFiltersProvider::UpdateCustomFilters(
+    const std::string& custom_filters) {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  if (!local_state_)
+    return false;
+  local_state_->SetString(prefs::kAdBlockCustomFilters, custom_filters);
+
+  auto buffer =
+      std::vector<unsigned char>(custom_filters.begin(), custom_filters.end());
+  OnDATLoaded(false, buffer);
+
+  return true;
+}
+
+void AdBlockCustomFiltersProvider::LoadDATBuffer(
+    base::OnceCallback<void(bool deserialize, const DATFileDataBuffer& dat_buf)>
+        cb) {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  auto custom_filters = GetCustomFilters();
+
+  auto buffer =
+      std::vector<unsigned char>(custom_filters.begin(), custom_filters.end());
+
+  // PostTask so this has an async return to match other loaders
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::BindOnce(std::move(cb), false, std::move(buffer)));
+}
+
+}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_custom_filters_provider.h b/components/brave_shields/browser/ad_block_custom_filters_provider.h
new file mode 100644
index 000000000000..b8fe59176a21
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_custom_filters_provider.h
@@ -0,0 +1,45 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_CUSTOM_FILTERS_PROVIDER_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_CUSTOM_FILTERS_PROVIDER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/sequence_checker.h"
+#include "brave/components/brave_component_updater/browser/dat_file_util.h"
+#include "brave/components/brave_shields/browser/ad_block_filters_provider.h"
+
+using brave_component_updater::DATFileDataBuffer;
+
+class PrefService;
+
+namespace brave_shields {
+
+class AdBlockCustomFiltersProvider : public AdBlockFiltersProvider {
+ public:
+  explicit AdBlockCustomFiltersProvider(PrefService* local_state);
+  ~AdBlockCustomFiltersProvider() override;
+  AdBlockCustomFiltersProvider(const AdBlockCustomFiltersProvider&) = delete;
+  AdBlockCustomFiltersProvider& operator=(const AdBlockCustomFiltersProvider&) =
+      delete;
+
+  std::string GetCustomFilters();
+  bool UpdateCustomFilters(const std::string& custom_filters);
+
+  void LoadDATBuffer(
+      base::OnceCallback<void(bool deserialize,
+                              const DATFileDataBuffer& dat_buf)>) override;
+
+ private:
+  PrefService* local_state_;
+
+  SEQUENCE_CHECKER(sequence_checker_);
+};
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_CUSTOM_FILTERS_PROVIDER_H_
diff --git a/components/brave_shields/browser/ad_block_custom_filters_service.cc b/components/brave_shields/browser/ad_block_custom_filters_service.cc
deleted file mode 100644
index ac8b7f80a453..000000000000
--- a/components/brave_shields/browser/ad_block_custom_filters_service.cc
+++ /dev/null
@@ -1,67 +0,0 @@
-/* Copyright (c) 2019 The Brave Authors. All rights reserved.
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
-
-#include "base/logging.h"
-#include "brave/components/adblock_rust_ffi/src/wrapper.h"
-#include "brave/components/brave_shields/browser/ad_block_service.h"
-#include "brave/components/brave_shields/common/pref_names.h"
-#include "components/prefs/pref_service.h"
-#include "content/public/browser/browser_thread.h"
-
-using brave_component_updater::BraveComponent;
-
-namespace brave_shields {
-
-AdBlockCustomFiltersService::AdBlockCustomFiltersService(
-    BraveComponent::Delegate* delegate)
-    : AdBlockBaseService(delegate) {}
-
-AdBlockCustomFiltersService::~AdBlockCustomFiltersService() {}
-
-bool AdBlockCustomFiltersService::Init() {
-  return UpdateCustomFilters(GetCustomFilters());
-}
-
-std::string AdBlockCustomFiltersService::GetCustomFilters() {
-  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  PrefService* local_state = delegate()->local_state();
-  if (!local_state)
-    return std::string();
-  return local_state->GetString(prefs::kAdBlockCustomFilters);
-}
-
-bool AdBlockCustomFiltersService::UpdateCustomFilters(
-    const std::string& custom_filters) {
-  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  PrefService* local_state = delegate()->local_state();
-  if (!local_state)
-    return false;
-  local_state->SetString(prefs::kAdBlockCustomFilters, custom_filters);
-
-  GetTaskRunner()->PostTask(
-      FROM_HERE,
-      base::BindOnce(
-          &AdBlockCustomFiltersService::UpdateCustomFiltersOnFileTaskRunner,
-          base::Unretained(this), custom_filters));
-
-  return true;
-}
-
-void AdBlockCustomFiltersService::UpdateCustomFiltersOnFileTaskRunner(
-    const std::string& custom_filters) {
-  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
-  ad_block_client_.reset(new adblock::Engine(custom_filters.c_str()));
-}
-
-///////////////////////////////////////////////////////////////////////////////
-
-std::unique_ptr<AdBlockCustomFiltersService> AdBlockCustomFiltersServiceFactory(
-    BraveComponent::Delegate* delegate) {
-  return std::make_unique<AdBlockCustomFiltersService>(delegate);
-}
-
-}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_custom_filters_service.h b/components/brave_shields/browser/ad_block_custom_filters_service.h
deleted file mode 100644
index c130d336a9e8..000000000000
--- a/components/brave_shields/browser/ad_block_custom_filters_service.h
+++ /dev/null
@@ -1,49 +0,0 @@
-/* Copyright (c) 2019 The Brave Authors. All rights reserved.
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_CUSTOM_FILTERS_SERVICE_H_
-#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_CUSTOM_FILTERS_SERVICE_H_
-
-#include <map>
-#include <memory>
-#include <string>
-#include <vector>
-
-#include "brave/components/brave_shields/browser/ad_block_base_service.h"
-
-class AdBlockServiceTest;
-
-using brave_component_updater::BraveComponent;
-
-namespace brave_shields {
-
-// The brave shields service in charge of custom filter ad-block
-// checking and init.
-class AdBlockCustomFiltersService : public AdBlockBaseService {
- public:
-  explicit AdBlockCustomFiltersService(BraveComponent::Delegate* delegate);
-  AdBlockCustomFiltersService(const AdBlockCustomFiltersService&) = delete;
-  AdBlockCustomFiltersService& operator=(const AdBlockCustomFiltersService&) =
-      delete;
-  ~AdBlockCustomFiltersService() override;
-
-  std::string GetCustomFilters();
-  bool UpdateCustomFilters(const std::string& custom_filters);
-
- protected:
-  bool Init() override;
-
- private:
-  friend class ::AdBlockServiceTest;
-  void UpdateCustomFiltersOnFileTaskRunner(const std::string& custom_filters);
-};
-
-// Creates the AdBlockCustomFiltersService
-std::unique_ptr<AdBlockCustomFiltersService>
-AdBlockCustomFiltersServiceFactory(BraveComponent::Delegate* delegate);
-
-}  // namespace brave_shields
-
-#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_CUSTOM_FILTERS_SERVICE_H_
diff --git a/components/brave_shields/browser/ad_block_default_filters_provider.cc b/components/brave_shields/browser/ad_block_default_filters_provider.cc
new file mode 100644
index 000000000000..a49d2b8ea4cc
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_default_filters_provider.cc
@@ -0,0 +1,113 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "brave/components/brave_shields/browser/ad_block_default_filters_provider.h"
+
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "base/task/thread_pool.h"
+#include "brave/components/brave_shields/browser/ad_block_component_installer.h"
+#include "content/public/browser/browser_task_traits.h"
+
+#define DAT_FILE "rs-ABPFilterParserData.dat"
+#define REGIONAL_CATALOG "regional_catalog.json"
+const char kAdBlockResourcesFilename[] = "resources.json";
+
+namespace brave_shields {
+
+AdBlockDefaultFiltersProvider::AdBlockDefaultFiltersProvider(
+    component_updater::ComponentUpdateService* cus) {
+  // Can be nullptr in unit tests
+  if (cus) {
+    RegisterAdBlockDefaultComponent(
+        cus,
+        base::BindRepeating(&AdBlockDefaultFiltersProvider::OnComponentReady,
+                            weak_factory_.GetWeakPtr()));
+  }
+}
+
+AdBlockDefaultFiltersProvider::~AdBlockDefaultFiltersProvider() {}
+
+void AdBlockDefaultFiltersProvider::OnComponentReady(
+    const base::FilePath& path) {
+  component_path_ = path;
+
+  // Load the DAT (as a buffer)
+  base::ThreadPool::PostTaskAndReplyWithResult(
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&brave_component_updater::ReadDATFileData,
+                     component_path_.AppendASCII(DAT_FILE)),
+      base::BindOnce(&AdBlockDefaultFiltersProvider::OnDATLoaded,
+                     weak_factory_.GetWeakPtr(), true));
+
+  // Load the resources (as a string)
+  base::ThreadPool::PostTaskAndReplyWithResult(
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&brave_component_updater::GetDATFileAsString,
+                     component_path_.AppendASCII(kAdBlockResourcesFilename)),
+      base::BindOnce(&AdBlockDefaultFiltersProvider::OnResourcesLoaded,
+                     weak_factory_.GetWeakPtr()));
+
+  // Load the regional catalog (as a string)
+  base::ThreadPool::PostTaskAndReplyWithResult(
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&brave_component_updater::GetDATFileAsString,
+                     component_path_.AppendASCII(REGIONAL_CATALOG)),
+      base::BindOnce(&AdBlockDefaultFiltersProvider::OnRegionalCatalogLoaded,
+                     weak_factory_.GetWeakPtr()));
+}
+
+void AdBlockDefaultFiltersProvider::LoadDATBuffer(
+    base::OnceCallback<void(bool deserialize, const DATFileDataBuffer& dat_buf)>
+        cb) {
+  if (component_path_.empty()) {
+    // If the path is not ready yet, don't run the callback. An update should
+    // be pushed soon.
+    return;
+  }
+
+  base::ThreadPool::PostTaskAndReplyWithResult(
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&brave_component_updater::ReadDATFileData,
+                     component_path_.AppendASCII(DAT_FILE)),
+      base::BindOnce(std::move(cb), true));
+}
+
+void AdBlockDefaultFiltersProvider::LoadResources(
+    base::OnceCallback<void(const std::string& resources_json)> cb) {
+  if (component_path_.empty()) {
+    // If the path is not ready yet, run the callback with empty resources to
+    // avoid blocking filter data loads.
+    std::move(cb).Run("[]");
+    return;
+  }
+
+  base::ThreadPool::PostTaskAndReplyWithResult(
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&brave_component_updater::GetDATFileAsString,
+                     component_path_.AppendASCII(kAdBlockResourcesFilename)),
+      std::move(cb));
+}
+
+void AdBlockDefaultFiltersProvider::LoadRegionalCatalog(
+    base::OnceCallback<void(const std::string& catalog_json)> cb) {
+  if (component_path_.empty()) {
+    // If the path is not ready yet, don't run the callback. An update should be
+    // pushed soon.
+    return;
+  }
+
+  base::ThreadPool::PostTaskAndReplyWithResult(
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&brave_component_updater::GetDATFileAsString,
+                     component_path_.AppendASCII(REGIONAL_CATALOG)),
+      std::move(cb));
+}
+
+}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_default_filters_provider.h b/components/brave_shields/browser/ad_block_default_filters_provider.h
new file mode 100644
index 000000000000..84ea9cbfacf5
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_default_filters_provider.h
@@ -0,0 +1,65 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_DEFAULT_FILTERS_PROVIDER_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_DEFAULT_FILTERS_PROVIDER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/observer_list.h"
+#include "brave/components/brave_component_updater/browser/dat_file_util.h"
+#include "brave/components/brave_shields/browser/ad_block_filters_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_regional_catalog_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_resource_provider.h"
+#include "third_party/abseil-cpp/absl/types/optional.h"
+
+using brave_component_updater::DATFileDataBuffer;
+
+namespace component_updater {
+class ComponentUpdateService;
+}  // namespace component_updater
+
+namespace base {
+class FilePath;
+}
+
+class AdBlockServiceTest;
+
+namespace brave_shields {
+
+class AdBlockDefaultFiltersProvider : public AdBlockFiltersProvider,
+                                      public AdBlockResourceProvider,
+                                      public AdBlockRegionalCatalogProvider {
+ public:
+  explicit AdBlockDefaultFiltersProvider(
+      component_updater::ComponentUpdateService* cus);
+  ~AdBlockDefaultFiltersProvider() override;
+  AdBlockDefaultFiltersProvider(const AdBlockDefaultFiltersProvider&) = delete;
+  AdBlockDefaultFiltersProvider& operator=(
+      const AdBlockDefaultFiltersProvider&) = delete;
+
+  void LoadDATBuffer(
+      base::OnceCallback<void(bool deserialize,
+                              const DATFileDataBuffer& dat_buf)>) override;
+
+  void LoadResources(
+      base::OnceCallback<void(const std::string& resources_json)>) override;
+
+  void LoadRegionalCatalog(
+      base::OnceCallback<void(const std::string& catalog_json)>) override;
+
+ private:
+  friend class ::AdBlockServiceTest;
+  void OnComponentReady(const base::FilePath&);
+
+  base::FilePath component_path_;
+
+  base::WeakPtrFactory<AdBlockDefaultFiltersProvider> weak_factory_{this};
+};
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_DEFAULT_FILTERS_PROVIDER_H_
diff --git a/components/brave_shields/browser/ad_block_base_service.cc b/components/brave_shields/browser/ad_block_engine.cc
similarity index 55%
rename from components/brave_shields/browser/ad_block_base_service.cc
rename to components/brave_shields/browser/ad_block_engine.cc
index b76702763d33..c1e554ecceb8 100644
--- a/components/brave_shields/browser/ad_block_base_service.cc
+++ b/components/brave_shields/browser/ad_block_engine.cc
@@ -1,9 +1,9 @@
-/* Copyright (c) 2019 The Brave Authors. All rights reserved.
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "brave/components/brave_shields/browser/ad_block_base_service.h"
+#include "brave/components/brave_shields/browser/ad_block_engine.h"
 
 #include <algorithm>
 #include <set>
@@ -16,19 +16,13 @@
 #include "base/json/json_reader.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/utf_string_conversions.h"
-#include "base/task/post_task.h"
-#include "base/task/thread_pool.h"
 #include "brave/components/adblock_rust_ffi/src/wrapper.h"
 #include "brave/components/brave_component_updater/browser/dat_file_util.h"
 #include "brave/components/brave_shields/common/brave_shield_constants.h"
-#include "content/public/browser/browser_task_traits.h"
-#include "content/public/browser/browser_thread.h"
 #include "net/base/registry_controlled_domains/registry_controlled_domain.h"
 #include "third_party/abseil-cpp/absl/types/optional.h"
 #include "url/origin.h"
 
-using brave_component_updater::BraveComponent;
-using content::BrowserThread;
 using namespace net::registry_controlled_domains;  // NOLINT
 
 namespace {
@@ -103,28 +97,18 @@ std::string ResourceTypeToString(blink::mojom::ResourceType resource_type) {
 
 namespace brave_shields {
 
-AdBlockBaseService::AdBlockBaseService(BraveComponent::Delegate* delegate)
-    : BaseBraveShieldsService(delegate),
-      ad_block_client_(new adblock::Engine()),
-      weak_factory_(this) {}
+AdBlockEngine::AdBlockEngine() : ad_block_client_(new adblock::Engine()) {}
 
-AdBlockBaseService::~AdBlockBaseService() {
-  GetTaskRunner()->DeleteSoon(FROM_HERE, ad_block_client_.release());
-}
-
-void AdBlockBaseService::ShouldStartRequest(
-    const GURL& url,
-    blink::mojom::ResourceType resource_type,
-    const std::string& tab_host,
-    bool aggressive_blocking,
-    bool* did_match_rule,
-    bool* did_match_exception,
-    bool* did_match_important,
-    std::string* mock_data_url) {
-  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
-  // if (!IsInitialized())
-  //   return;
+AdBlockEngine::~AdBlockEngine() {}
 
+void AdBlockEngine::ShouldStartRequest(const GURL& url,
+                                       blink::mojom::ResourceType resource_type,
+                                       const std::string& tab_host,
+                                       bool aggressive_blocking,
+                                       bool* did_match_rule,
+                                       bool* did_match_exception,
+                                       bool* did_match_important,
+                                       std::string* mock_data_url) {
   // Determine third-party here so the library doesn't need to figure it out.
   // CreateFromNormalizedTuple is needed because SameDomainOrHost needs
   // a URL or origin and not a string to a host name.
@@ -137,18 +121,16 @@ void AdBlockBaseService::ShouldStartRequest(
                             did_match_exception, did_match_important,
                             mock_data_url);
 
-  // LOG(ERROR) << "AdBlockBaseService::ShouldStartRequest(), host: "
+  // LOG(ERROR) << "AdBlockEngine::ShouldStartRequest(), host: "
   //  << tab_host
   //  << ", resource type: " << resource_type
   //  << ", url.spec(): " << url.spec();
 }
 
-absl::optional<std::string> AdBlockBaseService::GetCspDirectives(
+absl::optional<std::string> AdBlockEngine::GetCspDirectives(
     const GURL& url,
     blink::mojom::ResourceType resource_type,
     const std::string& tab_host) {
-  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
-
   // Determine third-party here so the library doesn't need to figure it out.
   // CreateFromNormalizedTuple is needed because SameDomainOrHost needs
   // a URL or origin and not a string to a host name.
@@ -167,14 +149,7 @@ absl::optional<std::string> AdBlockBaseService::GetCspDirectives(
   }
 }
 
-void AdBlockBaseService::EnableTag(const std::string& tag, bool enabled) {
-  if (BrowserThread::CurrentlyOn(BrowserThread::UI)) {
-    GetTaskRunner()->PostTask(
-        FROM_HERE, base::BindOnce(&AdBlockBaseService::EnableTag,
-                                  base::Unretained(this), tag, enabled));
-    return;
-  }
-
+void AdBlockEngine::EnableTag(const std::string& tag, bool enabled) {
   if (enabled) {
     if (tags_.find(tag) == tags_.end()) {
       ad_block_client_->addTag(tag);
@@ -190,39 +165,23 @@ void AdBlockBaseService::EnableTag(const std::string& tag, bool enabled) {
   }
 }
 
-void AdBlockBaseService::AddResources(const std::string& resources) {
-  if (BrowserThread::CurrentlyOn(BrowserThread::UI)) {
-    GetTaskRunner()->PostTask(
-        FROM_HERE, base::BindOnce(&AdBlockBaseService::AddResources,
-                                  base::Unretained(this), resources));
-    return;
-  }
-
+void AdBlockEngine::AddResources(const std::string& resources) {
   ad_block_client_->addResources(resources);
-  resources_ = resources;
 }
 
-bool AdBlockBaseService::TagExists(const std::string& tag) {
+bool AdBlockEngine::TagExists(const std::string& tag) {
   return std::find(tags_.begin(), tags_.end(), tag) != tags_.end();
 }
 
-absl::optional<base::Value> AdBlockBaseService::UrlCosmeticResources(
+absl::optional<base::Value> AdBlockEngine::UrlCosmeticResources(
     const std::string& url) {
-  // if (!IsInitialized())
-  //   return;
-
-  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
   return base::JSONReader::Read(ad_block_client_->urlCosmeticResources(url));
 }
 
-base::Value AdBlockBaseService::HiddenClassIdSelectors(
+base::Value AdBlockEngine::HiddenClassIdSelectors(
     const std::vector<std::string>& classes,
     const std::vector<std::string>& ids,
     const std::vector<std::string>& exceptions) {
-  // if (!IsInitialized())
-  //   return;
-
-  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
   absl::optional<base::Value> result = base::JSONReader::Read(
       ad_block_client_->hiddenClassIdSelectors(classes, ids, exceptions));
 
@@ -233,73 +192,60 @@ base::Value AdBlockBaseService::HiddenClassIdSelectors(
   }
 }
 
-void AdBlockBaseService::GetDATFileData(const base::FilePath& dat_file_path,
-                                        bool deserialize,
-                                        base::OnceClosure callback) {
-  base::ThreadPool::PostTaskAndReplyWithResult(
-      FROM_HERE, {base::MayBlock()},
-      base::BindOnce(
-          deserialize
-              ? &brave_component_updater::LoadDATFileData<adblock::Engine>
-              : &brave_component_updater::LoadRawFileData<adblock::Engine>,
-          dat_file_path),
-      base::BindOnce(&AdBlockBaseService::OnGetDATFileData,
-                     weak_factory_.GetWeakPtr(), std::move(callback)));
-}
-
-void AdBlockBaseService::OnGetDATFileData(base::OnceClosure callback,
-                                          GetDATFileDataResult result) {
-  if (result.second.empty()) {
-    LOG(ERROR) << "Could not obtain ad block data";
-    return;
-  }
-  if (!result.first.get()) {
-    LOG(ERROR) << "Failed to deserialize ad block data";
-    return;
+void AdBlockEngine::Load(bool deserialize,
+                         const DATFileDataBuffer& dat_buf,
+                         const std::string& resources_json) {
+  if (deserialize) {
+    OnDATLoaded(dat_buf, resources_json);
+  } else {
+    OnListSourceLoaded(dat_buf, resources_json);
   }
-  GetTaskRunner()->PostTask(
-      FROM_HERE, base::BindOnce(&AdBlockBaseService::UpdateAdBlockClient,
-                                base::Unretained(this),
-                                std::move(result.first)));
-  // TODO(bridiver) this needs to happen after adblock client is actually reset
-  std::move(callback).Run();
 }
 
-void AdBlockBaseService::UpdateAdBlockClient(
-    std::unique_ptr<adblock::Engine> ad_block_client) {
-  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
+void AdBlockEngine::UpdateAdBlockClient(
+    std::unique_ptr<adblock::Engine> ad_block_client,
+    const std::string& resources_json) {
   ad_block_client_ = std::move(ad_block_client);
+  AddResources(resources_json);
   AddKnownTagsToAdBlockInstance();
-  AddKnownResourcesToAdBlockInstance();
+  if (test_observer_) {
+    test_observer_->OnEngineUpdated();
+  }
 }
 
-void AdBlockBaseService::AddKnownTagsToAdBlockInstance() {
+void AdBlockEngine::AddKnownTagsToAdBlockInstance() {
   std::for_each(tags_.begin(), tags_.end(),
                 [&](const std::string tag) { ad_block_client_->addTag(tag); });
 }
 
-void AdBlockBaseService::AddKnownResourcesToAdBlockInstance() {
-  ad_block_client_->addResources(resources_);
+void AdBlockEngine::OnListSourceLoaded(const DATFileDataBuffer& filters,
+                                       const std::string& resources_json) {
+  UpdateAdBlockClient(
+      std::make_unique<adblock::Engine>(
+          reinterpret_cast<const char*>(filters.data()), filters.size()),
+      resources_json);
 }
 
-bool AdBlockBaseService::Init() {
-  return true;
+void AdBlockEngine::OnDATLoaded(const DATFileDataBuffer& dat_buf,
+                                const std::string& resources_json) {
+  // An empty buffer will not load successfully.
+  if (dat_buf.empty()) {
+    return;
+  }
+
+  auto client = std::make_unique<adblock::Engine>();
+  client->deserialize(reinterpret_cast<const char*>(&dat_buf.front()),
+                      dat_buf.size());
+
+  UpdateAdBlockClient(std::move(client), resources_json);
 }
 
-void AdBlockBaseService::ResetForTest(const std::string& rules,
-                                      const std::string& resources) {
-  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
-  // This is temporary until adblock-rust supports incrementally adding
-  // filter rules to an existing instance. At which point the hack below
-  // will dissapear.
-  ad_block_client_.reset(new adblock::Engine(rules));
-  AddKnownTagsToAdBlockInstance();
-  if (!resources.empty()) {
-    resources_ = resources;
-  }
-  AddKnownResourcesToAdBlockInstance();
+void AdBlockEngine::AddObserverForTest(AdBlockEngine::TestObserver* observer) {
+  test_observer_ = observer;
 }
 
-///////////////////////////////////////////////////////////////////////////////
+void AdBlockEngine::RemoveObserverForTest() {
+  test_observer_ = nullptr;
+}
 
 }  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_base_service.h b/components/brave_shields/browser/ad_block_engine.h
similarity index 56%
rename from components/brave_shields/browser/ad_block_base_service.h
rename to components/brave_shields/browser/ad_block_engine.h
index 569f5a6a3e9a..990fdd3ced74 100644
--- a/components/brave_shields/browser/ad_block_base_service.h
+++ b/components/brave_shields/browser/ad_block_engine.h
@@ -1,10 +1,10 @@
-/* Copyright (c) 2019 The Brave Authors. All rights reserved.
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_BASE_SERVICE_H_
-#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_BASE_SERVICE_H_
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_ENGINE_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_ENGINE_H_
 
 #include <stdint.h>
 
@@ -14,37 +14,35 @@
 #include <utility>
 #include <vector>
 
-#include "base/files/file_path.h"
 #include "base/memory/weak_ptr.h"
-#include "base/sequence_checker.h"
 #include "base/values.h"
 #include "brave/components/brave_component_updater/browser/dat_file_util.h"
-#include "brave/components/brave_shields/browser/base_brave_shields_service.h"
 #include "third_party/blink/public/mojom/loader/resource_load_info.mojom-shared.h"
+#include "url/gurl.h"
 
-class AdBlockServiceTest;
-class BraveAdBlockTPNetworkDelegateHelperTest;
-class EphemeralStorage1pDomainBlockBrowserTest;
-class PerfPredictorTabHelperTest;
+using brave_component_updater::DATFileDataBuffer;
 
-using brave_component_updater::BraveComponent;
 namespace adblock {
 class Engine;
 }
 
+class AdBlockServiceTest;
+class BraveAdBlockTPNetworkDelegateHelperTest;
+class EphemeralStorage1pDomainBlockBrowserTest;
+class PerfPredictorTabHelperTest;
+
 namespace brave_shields {
 
-// The base class of the brave shields service in charge of ad-block
-// checking and init.
-class AdBlockBaseService : public BaseBraveShieldsService {
+// Service managing an adblock engine.
+class AdBlockEngine : public base::SupportsWeakPtr<AdBlockEngine> {
  public:
   using GetDATFileDataResult =
       brave_component_updater::LoadDATFileDataResult<adblock::Engine>;
 
-  explicit AdBlockBaseService(BraveComponent::Delegate* delegate);
-  AdBlockBaseService(const AdBlockBaseService&) = delete;
-  AdBlockBaseService& operator=(const AdBlockBaseService&) = delete;
-  ~AdBlockBaseService() override;
+  AdBlockEngine();
+  AdBlockEngine(const AdBlockEngine&) = delete;
+  AdBlockEngine& operator=(const AdBlockEngine&) = delete;
+  ~AdBlockEngine();
 
   void ShouldStartRequest(const GURL& url,
                           blink::mojom::ResourceType resource_type,
@@ -53,7 +51,7 @@ class AdBlockBaseService : public BaseBraveShieldsService {
                           bool* did_match_rule,
                           bool* did_match_exception,
                           bool* did_match_important,
-                          std::string* mock_data_url) override;
+                          std::string* mock_data_url);
   absl::optional<std::string> GetCspDirectives(
       const GURL& url,
       blink::mojom::ResourceType resource_type,
@@ -62,41 +60,47 @@ class AdBlockBaseService : public BaseBraveShieldsService {
   void EnableTag(const std::string& tag, bool enabled);
   bool TagExists(const std::string& tag);
 
-  virtual absl::optional<base::Value> UrlCosmeticResources(
-      const std::string& url);
-  virtual base::Value HiddenClassIdSelectors(
+  absl::optional<base::Value> UrlCosmeticResources(const std::string& url);
+  base::Value HiddenClassIdSelectors(
       const std::vector<std::string>& classes,
       const std::vector<std::string>& ids,
       const std::vector<std::string>& exceptions);
 
- protected:
-  friend class ::AdBlockServiceTest;
-  friend class ::BraveAdBlockTPNetworkDelegateHelperTest;
-  friend class ::EphemeralStorage1pDomainBlockBrowserTest;
-  friend class ::PerfPredictorTabHelperTest;
+  void Load(bool deserialize,
+            const DATFileDataBuffer& dat_buf,
+            const std::string& resources_json);
 
-  bool Init() override;
+  class TestObserver : public base::CheckedObserver {
+   public:
+    virtual void OnEngineUpdated() = 0;
+  };
 
-  void GetDATFileData(const base::FilePath& dat_file_path,
-                      bool deserialize = true,
-                      base::OnceClosure callback = base::DoNothing());
+  void AddObserverForTest(TestObserver* observer);
+  void RemoveObserverForTest();
+
+ protected:
   void AddKnownTagsToAdBlockInstance();
-  void AddKnownResourcesToAdBlockInstance();
-  void ResetForTest(const std::string& rules, const std::string& resources);
+  void UpdateAdBlockClient(std::unique_ptr<adblock::Engine> ad_block_client,
+                           const std::string& resources_json);
+  void OnListSourceLoaded(const DATFileDataBuffer& filters,
+                          const std::string& resources_json);
+
+  void OnDATLoaded(const DATFileDataBuffer& dat_buf,
+                   const std::string& resources_json);
 
   std::unique_ptr<adblock::Engine> ad_block_client_;
 
  private:
-  void UpdateAdBlockClient(std::unique_ptr<adblock::Engine> ad_block_client);
-  void OnGetDATFileData(base::OnceClosure callback,
-                        GetDATFileDataResult result);
-  void OnPreferenceChanges(const std::string& pref_name);
+  friend class ::AdBlockServiceTest;
+  friend class ::BraveAdBlockTPNetworkDelegateHelperTest;
+  friend class ::EphemeralStorage1pDomainBlockBrowserTest;
+  friend class ::PerfPredictorTabHelperTest;
 
   std::set<std::string> tags_;
-  std::string resources_;
-  base::WeakPtrFactory<AdBlockBaseService> weak_factory_;
+
+  raw_ptr<TestObserver> test_observer_ = nullptr;
 };
 
 }  // namespace brave_shields
 
-#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_BASE_SERVICE_H_
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_ENGINE_H_
diff --git a/components/brave_shields/browser/ad_block_filters_provider.cc b/components/brave_shields/browser/ad_block_filters_provider.cc
new file mode 100644
index 000000000000..c21c5f292f9b
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_filters_provider.cc
@@ -0,0 +1,51 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "brave/components/brave_shields/browser/ad_block_filters_provider.h"
+
+namespace brave_shields {
+
+AdBlockFiltersProvider::AdBlockFiltersProvider() {}
+
+AdBlockFiltersProvider::~AdBlockFiltersProvider() {}
+
+void AdBlockFiltersProvider::AddObserver(
+    AdBlockFiltersProvider::Observer* observer) {
+  if (!observers_.HasObserver(observer))
+    observers_.AddObserver(observer);
+}
+
+void AdBlockFiltersProvider::RemoveObserver(
+    AdBlockFiltersProvider::Observer* observer) {
+  if (observers_.HasObserver(observer))
+    observers_.RemoveObserver(observer);
+}
+
+void AdBlockFiltersProvider::OnDATLoaded(bool deserialize,
+                                         const DATFileDataBuffer& dat_buf) {
+  for (auto& observer : observers_) {
+    observer.OnDATLoaded(deserialize, dat_buf);
+  }
+}
+
+void AdBlockFiltersProvider::LoadDAT(
+    AdBlockFiltersProvider::Observer* observer) {
+  LoadDATBuffer(base::BindOnce(&AdBlockFiltersProvider::OnLoad,
+                               weak_factory_.GetWeakPtr(), observer));
+}
+
+void AdBlockFiltersProvider::OnLoad(AdBlockFiltersProvider::Observer* observer,
+                                    bool deserialize,
+                                    const DATFileDataBuffer& dat_buf) {
+  if (observers_.HasObserver(observer)) {
+    observer->OnDATLoaded(deserialize, dat_buf);
+  }
+}
+
+bool AdBlockFiltersProvider::Delete() && {
+  return false;
+}
+
+}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_filters_provider.h b/components/brave_shields/browser/ad_block_filters_provider.h
new file mode 100644
index 000000000000..3e5a5cc94f5e
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_filters_provider.h
@@ -0,0 +1,57 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_FILTERS_PROVIDER_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_FILTERS_PROVIDER_H_
+
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
+#include "brave/components/brave_component_updater/browser/dat_file_util.h"
+
+using brave_component_updater::DATFileDataBuffer;
+
+namespace brave_shields {
+
+// Interface for any source that can load filters or serialized filter data
+// into an adblock engine.
+class AdBlockFiltersProvider {
+ public:
+  class Observer : public base::CheckedObserver {
+   public:
+    virtual void OnDATLoaded(bool deserialize,
+                             const DATFileDataBuffer& dat_buf) = 0;
+  };
+
+  AdBlockFiltersProvider();
+  AdBlockFiltersProvider(const AdBlockFiltersProvider&) = delete;
+  AdBlockFiltersProvider& operator=(const AdBlockFiltersProvider&) = delete;
+  virtual ~AdBlockFiltersProvider();
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  void LoadDAT(Observer* observer);
+
+  virtual bool Delete() &&;
+
+ protected:
+  virtual void LoadDATBuffer(
+      base::OnceCallback<void(bool deserialize,
+                              const DATFileDataBuffer& dat_buf)>) = 0;
+
+  void OnLoad(AdBlockFiltersProvider::Observer* observer,
+              bool deserialize,
+              const DATFileDataBuffer& dat_buf);
+  void OnDATLoaded(bool deserialize, const DATFileDataBuffer& dat_buf);
+
+ private:
+  base::ObserverList<Observer> observers_;
+  base::WeakPtrFactory<AdBlockFiltersProvider> weak_factory_{this};
+};
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_FILTERS_PROVIDER_H_
diff --git a/components/brave_shields/browser/ad_block_pref_service.cc b/components/brave_shields/browser/ad_block_pref_service.cc
index 8c787e1bf10c..29d0a0e59de5 100644
--- a/components/brave_shields/browser/ad_block_pref_service.cc
+++ b/components/brave_shields/browser/ad_block_pref_service.cc
@@ -6,7 +6,7 @@
 #include "brave/components/brave_shields/browser/ad_block_pref_service.h"
 
 #include "base/bind.h"
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
+#include "brave/components/brave_shields/browser/ad_block_engine.h"
 #include "brave/components/brave_shields/browser/ad_block_regional_service_manager.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/ad_block_subscription_service_manager.h"
diff --git a/components/brave_shields/browser/ad_block_regional_catalog_provider.cc b/components/brave_shields/browser/ad_block_regional_catalog_provider.cc
new file mode 100644
index 000000000000..5565e0fb5c25
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_regional_catalog_provider.cc
@@ -0,0 +1,33 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <string>
+
+#include "brave/components/brave_shields/browser/ad_block_regional_catalog_provider.h"
+
+namespace brave_shields {
+
+AdBlockRegionalCatalogProvider::AdBlockRegionalCatalogProvider() {}
+
+AdBlockRegionalCatalogProvider::~AdBlockRegionalCatalogProvider() {}
+
+void AdBlockRegionalCatalogProvider::AddObserver(
+    AdBlockRegionalCatalogProvider::Observer* observer) {
+  observers_.AddObserver(observer);
+}
+
+void AdBlockRegionalCatalogProvider::RemoveObserver(
+    AdBlockRegionalCatalogProvider::Observer* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+void AdBlockRegionalCatalogProvider::OnRegionalCatalogLoaded(
+    const std::string& catalog_json) {
+  for (auto& observer : observers_) {
+    observer.OnRegionalCatalogLoaded(catalog_json);
+  }
+}
+
+}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_regional_catalog_provider.h b/components/brave_shields/browser/ad_block_regional_catalog_provider.h
new file mode 100644
index 000000000000..d88d5b88eab7
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_regional_catalog_provider.h
@@ -0,0 +1,45 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_REGIONAL_CATALOG_PROVIDER_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_REGIONAL_CATALOG_PROVIDER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/observer_list.h"
+#include "brave/components/brave_component_updater/browser/dat_file_util.h"
+#include "third_party/abseil-cpp/absl/types/optional.h"
+
+using brave_component_updater::DATFileDataBuffer;
+
+namespace brave_shields {
+
+class AdBlockRegionalCatalogProvider {
+ public:
+  class Observer : public base::CheckedObserver {
+   public:
+    virtual void OnRegionalCatalogLoaded(const std::string& catalog_json) = 0;
+  };
+
+  AdBlockRegionalCatalogProvider();
+  virtual ~AdBlockRegionalCatalogProvider();
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  virtual void LoadRegionalCatalog(
+      base::OnceCallback<void(const std::string& catalog_json)>) = 0;
+
+ protected:
+  void OnRegionalCatalogLoaded(const std::string& catalog_json);
+
+ private:
+  base::ObserverList<Observer> observers_;
+};
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_REGIONAL_CATALOG_PROVIDER_H_
diff --git a/components/brave_shields/browser/ad_block_regional_filters_provider.cc b/components/brave_shields/browser/ad_block_regional_filters_provider.cc
new file mode 100644
index 000000000000..a49b0e07ed67
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_regional_filters_provider.cc
@@ -0,0 +1,77 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "brave/components/brave_shields/browser/ad_block_regional_filters_provider.h"
+
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "base/task/thread_pool.h"
+#include "brave/components/brave_shields/browser/ad_block_component_installer.h"
+#include "components/component_updater/component_updater_service.h"
+#include "content/public/browser/browser_task_traits.h"
+
+namespace brave_shields {
+
+AdBlockRegionalFiltersProvider::AdBlockRegionalFiltersProvider(
+    component_updater::ComponentUpdateService* cus,
+    const adblock::FilterList& catalog_entry)
+    : uuid_(catalog_entry.uuid),
+      component_id_(catalog_entry.component_id),
+      component_updater_service_(cus) {
+  // Can be nullptr in unit tests
+  if (cus) {
+    RegisterAdBlockRegionalComponent(
+        component_updater_service_, catalog_entry.base64_public_key,
+        component_id_, catalog_entry.title,
+        base::BindRepeating(&AdBlockRegionalFiltersProvider::OnComponentReady,
+                            weak_factory_.GetWeakPtr()));
+  }
+}
+
+AdBlockRegionalFiltersProvider::~AdBlockRegionalFiltersProvider() {}
+
+void AdBlockRegionalFiltersProvider::OnComponentReady(
+    const base::FilePath& path) {
+  component_path_ = path;
+
+  base::FilePath dat_file_path =
+      component_path_.AppendASCII(std::string("rs-") + uuid_)
+          .AddExtension(FILE_PATH_LITERAL(".dat"));
+
+  base::ThreadPool::PostTaskAndReplyWithResult(
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&brave_component_updater::ReadDATFileData, dat_file_path),
+      base::BindOnce(&AdBlockRegionalFiltersProvider::OnDATLoaded,
+                     weak_factory_.GetWeakPtr(), true));
+}
+
+void AdBlockRegionalFiltersProvider::LoadDATBuffer(
+    base::OnceCallback<void(bool deserialize, const DATFileDataBuffer& dat_buf)>
+        cb) {
+  if (component_path_.empty()) {
+    // If the path is not ready yet, do nothing. An update should be pushed
+    // soon.
+    return;
+  }
+
+  base::FilePath dat_file_path =
+      component_path_.AppendASCII(std::string("rs-") + uuid_)
+          .AddExtension(FILE_PATH_LITERAL(".dat"));
+
+  base::ThreadPool::PostTaskAndReplyWithResult(
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&brave_component_updater::ReadDATFileData, dat_file_path),
+      base::BindOnce(std::move(cb), true));
+}
+
+bool AdBlockRegionalFiltersProvider::Delete() && {
+  return component_updater_service_->UnregisterComponent(component_id_);
+}
+
+}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_regional_filters_provider.h b/components/brave_shields/browser/ad_block_regional_filters_provider.h
new file mode 100644
index 000000000000..f6a0e63e9d34
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_regional_filters_provider.h
@@ -0,0 +1,62 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_REGIONAL_FILTERS_PROVIDER_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_REGIONAL_FILTERS_PROVIDER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/observer_list.h"
+#include "brave/components/adblock_rust_ffi/src/wrapper.h"
+#include "brave/components/brave_component_updater/browser/dat_file_util.h"
+#include "brave/components/brave_shields/browser/ad_block_filters_provider.h"
+#include "third_party/abseil-cpp/absl/types/optional.h"
+
+namespace component_updater {
+class ComponentUpdateService;
+}  // namespace component_updater
+
+namespace base {
+class FilePath;
+}
+
+class AdBlockServiceTest;
+
+namespace brave_shields {
+
+class AdBlockRegionalFiltersProvider : public AdBlockFiltersProvider {
+ public:
+  AdBlockRegionalFiltersProvider(component_updater::ComponentUpdateService* cus,
+                                 const adblock::FilterList& catalog_entry);
+  ~AdBlockRegionalFiltersProvider() override;
+  AdBlockRegionalFiltersProvider(const AdBlockRegionalFiltersProvider&) =
+      delete;
+  AdBlockRegionalFiltersProvider& operator=(
+      const AdBlockRegionalFiltersProvider&) = delete;
+
+  void LoadDATBuffer(
+      base::OnceCallback<void(
+          bool deserialize,
+          const brave_component_updater::DATFileDataBuffer& dat_buf)>) override;
+
+  bool Delete() && override;
+
+ private:
+  friend class ::AdBlockServiceTest;
+
+  void OnComponentReady(const base::FilePath&);
+
+  base::FilePath component_path_;
+  std::string uuid_;
+  std::string component_id_;
+  component_updater::ComponentUpdateService* component_updater_service_;
+
+  base::WeakPtrFactory<AdBlockRegionalFiltersProvider> weak_factory_{this};
+};
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_REGIONAL_FILTERS_PROVIDER_H_
diff --git a/components/brave_shields/browser/ad_block_regional_service.cc b/components/brave_shields/browser/ad_block_regional_service.cc
deleted file mode 100644
index 7477fabee28b..000000000000
--- a/components/brave_shields/browser/ad_block_regional_service.cc
+++ /dev/null
@@ -1,111 +0,0 @@
-/* Copyright (c) 2019 The Brave Authors. All rights reserved.
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#include "brave/components/brave_shields/browser/ad_block_regional_service.h"
-
-#include <algorithm>
-#include <string>
-#include <utility>
-#include <vector>
-
-#include "base/base_paths.h"
-#include "base/files/file_path.h"
-#include "base/logging.h"
-#include "base/memory/ptr_util.h"
-#include "base/strings/string_number_conversions.h"
-#include "base/strings/utf_string_conversions.h"
-#include "base/threading/thread_restrictions.h"
-#include "brave/components/adblock_rust_ffi/src/wrapper.h"
-#include "brave/components/brave_shields/browser/ad_block_regional_service_manager.h"
-#include "brave/components/brave_shields/browser/ad_block_service.h"
-#include "brave/components/brave_shields/browser/ad_block_service_helper.h"
-#include "components/prefs/pref_service.h"
-
-namespace brave_shields {
-
-std::string                                                     // NOLINT
-    AdBlockRegionalService::g_ad_block_regional_component_id_;  // NOLINT
-std::string AdBlockRegionalService::                            // NOLINT
-    g_ad_block_regional_component_base64_public_key_;           // NOLINT
-
-AdBlockRegionalService::AdBlockRegionalService(
-    const adblock::FilterList& catalog_entry,
-    brave_component_updater::BraveComponent::Delegate* delegate,
-    AdBlockRegionalService::ResourcesFileReadyCallback
-        resoures_file_ready_callback)
-    : AdBlockBaseService(delegate),
-      resoures_file_ready_callback_(resoures_file_ready_callback),
-      uuid_(catalog_entry.uuid),
-      title_(catalog_entry.title),
-      component_id_(catalog_entry.component_id),
-      base64_public_key_(catalog_entry.base64_public_key) {}
-
-AdBlockRegionalService::~AdBlockRegionalService() {}
-
-void AdBlockRegionalService::SetCatalogEntry(const adblock::FilterList& entry) {
-  DCHECK(entry.uuid == uuid_);
-  title_ = entry.title;
-  component_id_ = entry.component_id;
-  base64_public_key_ = entry.base64_public_key;
-}
-
-bool AdBlockRegionalService::Init() {
-  AdBlockBaseService::Init();
-
-  Register(title_,
-           !g_ad_block_regional_component_id_.empty()
-               ? g_ad_block_regional_component_id_
-               : component_id_,
-           !g_ad_block_regional_component_base64_public_key_.empty()
-               ? g_ad_block_regional_component_base64_public_key_
-               : base64_public_key_);
-
-  return true;
-}
-
-void AdBlockRegionalService::OnComponentReady(const std::string& component_id,
-                                              const base::FilePath& install_dir,
-                                              const std::string& manifest) {
-  base::FilePath dat_file_path =
-      install_dir.AppendASCII(std::string("rs-") + uuid_)
-          .AddExtension(FILE_PATH_LITERAL(".dat"));
-  GetDATFileData(dat_file_path);
-  base::FilePath resources_file_path =
-      install_dir.AppendASCII(kAdBlockResourcesFilename);
-
-  base::PostTaskAndReplyWithResult(
-      GetTaskRunner().get(), FROM_HERE,
-      base::BindOnce(&brave_component_updater::GetDATFileAsString,
-                     resources_file_path),
-      base::BindOnce(&AdBlockRegionalService::OnResourcesFileDataReady,
-                     weak_factory_.GetWeakPtr()));
-}
-
-void AdBlockRegionalService::OnResourcesFileDataReady(
-    const std::string& resources) {
-  resoures_file_ready_callback_.Run(resources);
-}
-
-// static
-void AdBlockRegionalService::SetComponentIdAndBase64PublicKeyForTest(
-    const std::string& component_id,
-    const std::string& component_base64_public_key) {
-  g_ad_block_regional_component_id_ = component_id;
-  g_ad_block_regional_component_base64_public_key_ =
-      component_base64_public_key;
-}
-
-///////////////////////////////////////////////////////////////////////////////
-
-std::unique_ptr<AdBlockRegionalService> AdBlockRegionalServiceFactory(
-    const adblock::FilterList& catalog_entry,
-    brave_component_updater::BraveComponent::Delegate* delegate,
-    AdBlockRegionalService::ResourcesFileReadyCallback
-        resoures_file_ready_callback) {
-  return std::make_unique<AdBlockRegionalService>(catalog_entry, delegate,
-                                                  resoures_file_ready_callback);
-}
-
-}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_regional_service.h b/components/brave_shields/browser/ad_block_regional_service.h
deleted file mode 100644
index 616fb11e586d..000000000000
--- a/components/brave_shields/browser/ad_block_regional_service.h
+++ /dev/null
@@ -1,79 +0,0 @@
-/* Copyright (c) 2019 The Brave Authors. All rights reserved.
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_REGIONAL_SERVICE_H_
-#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_REGIONAL_SERVICE_H_
-
-#include <stdint.h>
-
-#include <memory>
-#include <string>
-#include <vector>
-
-#include "base/callback.h"
-#include "base/files/file_path.h"
-#include "brave/components/adblock_rust_ffi/src/wrapper.h"
-#include "brave/components/brave_shields/browser/ad_block_base_service.h"
-
-class AdBlockServiceTest;
-
-namespace brave_shields {
-
-// The brave shields service in charge of ad-block checking and init
-// for a specific region.
-class AdBlockRegionalService : public AdBlockBaseService {
- public:
-  using ResourcesFileReadyCallback =
-      base::RepeatingCallback<void(const std::string&)>;
-
-  explicit AdBlockRegionalService(
-      const adblock::FilterList& catalog_entry,
-      brave_component_updater::BraveComponent::Delegate* delegate,
-      ResourcesFileReadyCallback resoures_file_ready_callback);
-  AdBlockRegionalService(const AdBlockRegionalService&) = delete;
-  AdBlockRegionalService& operator=(const AdBlockRegionalService&) = delete;
-  ~AdBlockRegionalService() override;
-
-  void SetCatalogEntry(const adblock::FilterList& entry);
-
-  std::string GetUUID() const { return uuid_; }
-  std::string GetTitle() const { return title_; }
-
- protected:
-  bool Init() override;
-  void OnComponentReady(const std::string& component_id,
-                        const base::FilePath& install_dir,
-                        const std::string& manifest) override;
-  void OnResourcesFileDataReady(const std::string& resources);
-
- private:
-  friend class ::AdBlockServiceTest;
-  static std::string g_ad_block_regional_component_id_;
-  static std::string g_ad_block_regional_component_base64_public_key_;
-  static std::string g_ad_block_regional_dat_file_version_;
-  static void SetComponentIdAndBase64PublicKeyForTest(
-      const std::string& component_id,
-      const std::string& component_base64_public_key);
-
-  ResourcesFileReadyCallback resoures_file_ready_callback_;
-
-  std::string uuid_;
-  std::string title_;
-  std::string component_id_;
-  std::string base64_public_key_;
-
-  base::WeakPtrFactory<AdBlockRegionalService> weak_factory_{this};
-};
-
-// Creates the AdBlockRegionalService
-std::unique_ptr<AdBlockRegionalService> AdBlockRegionalServiceFactory(
-    const adblock::FilterList& catalog_entry,
-    brave_component_updater::BraveComponent::Delegate* delegate,
-    AdBlockRegionalService::ResourcesFileReadyCallback
-        resoures_file_ready_callback);
-
-}  // namespace brave_shields
-
-#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_REGIONAL_SERVICE_H_
diff --git a/components/brave_shields/browser/ad_block_regional_service_manager.cc b/components/brave_shields/browser/ad_block_regional_service_manager.cc
index bc70fe04c442..0c75b81b82a9 100644
--- a/components/brave_shields/browser/ad_block_regional_service_manager.cc
+++ b/components/brave_shields/browser/ad_block_regional_service_manager.cc
@@ -14,9 +14,10 @@
 #include "base/task/post_task.h"
 #include "base/values.h"
 #include "brave/components/adblock_rust_ffi/src/wrapper.h"
-#include "brave/components/brave_shields/browser/ad_block_regional_service.h"
+#include "brave/components/brave_shields/browser/ad_block_engine.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/ad_block_service_helper.h"
+#include "brave/components/brave_shields/common/brave_shield_constants.h"
 #include "brave/components/brave_shields/common/features.h"
 #include "brave/components/brave_shields/common/pref_names.h"
 #include "components/prefs/pref_service.h"
@@ -27,23 +28,39 @@
 using adblock::FilterList;
 using brave_shields::features::kBraveAdblockCookieListDefault;
 
-const char kCookieListUuid[] = "AC023D22-AE88-4060-A978-4FEEEC4221693";
-
 namespace brave_shields {
 
 AdBlockRegionalServiceManager::AdBlockRegionalServiceManager(
-    brave_component_updater::BraveComponent::Delegate* delegate)
-    : delegate_(delegate),
-      initialized_(false) {
+    PrefService* local_state,
+    std::string locale,
+    component_updater::ComponentUpdateService* cus,
+    scoped_refptr<base::SequencedTaskRunner> task_runner)
+    : local_state_(local_state),
+      locale_(locale),
+      initialized_(false),
+      task_runner_(task_runner),
+      component_update_service_(cus) {}
+
+void AdBlockRegionalServiceManager::Init(
+    AdBlockResourceProvider* resource_provider,
+    AdBlockRegionalCatalogProvider* catalog_provider) {
+  DCHECK(!initialized_);
+  resource_provider_ = resource_provider;
+  catalog_provider_ = catalog_provider;
+  catalog_provider_->LoadRegionalCatalog(
+      base::BindOnce(&AdBlockRegionalServiceManager::OnRegionalCatalogLoaded,
+                     weak_factory_.GetWeakPtr()));
+  catalog_provider_->AddObserver(this);
+  initialized_ = true;
 }
 
 AdBlockRegionalServiceManager::~AdBlockRegionalServiceManager() {
+  catalog_provider_->RemoveObserver(this);
 }
 
 void AdBlockRegionalServiceManager::StartRegionalServices() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  PrefService* local_state = delegate_->local_state();
-  if (!local_state)
+  if (!local_state_)
     return;
 
   if (regional_catalog_.size() == 0) {
@@ -53,24 +70,24 @@ void AdBlockRegionalServiceManager::StartRegionalServices() {
   // Enable the default regional list, but only do this once so that
   // user can override this setting in the future
   bool checked_default_region =
-      local_state->GetBoolean(prefs::kAdBlockCheckedDefaultRegion);
+      local_state_->GetBoolean(prefs::kAdBlockCheckedDefaultRegion);
   if (!checked_default_region) {
-    local_state->SetBoolean(prefs::kAdBlockCheckedDefaultRegion, true);
+    local_state_->SetBoolean(prefs::kAdBlockCheckedDefaultRegion, true);
     auto it = brave_shields::FindAdBlockFilterListByLocale(regional_catalog_,
-                                                           delegate_->locale());
+                                                           locale_);
     if (it == regional_catalog_.end())
       return;
     EnableFilterList(it->uuid, true);
   }
 
   const bool cookie_list_touched =
-      local_state->GetBoolean(prefs::kAdBlockCookieListSettingTouched);
+      local_state_->GetBoolean(prefs::kAdBlockCookieListSettingTouched);
 
   // Start all regional services associated with enabled filter lists
   base::AutoLock lock(regional_services_lock_);
   const base::DictionaryValue* regional_filters_dict =
       &base::Value::AsDictionaryValue(
-          *local_state->GetDictionary(prefs::kAdBlockRegionalFilters));
+          *local_state_->GetDictionary(prefs::kAdBlockRegionalFilters));
 
   base::Value regional_filters_dict_with_cookielist =
       base::Value(regional_filters_dict->Clone());
@@ -91,51 +108,51 @@ void AdBlockRegionalServiceManager::StartRegionalServices() {
       enabled = regional_filter_dict->FindBoolKey("enabled").value_or(false);
     }
     if (enabled) {
-      auto catalog_entry = brave_shields::FindAdBlockFilterListByUUID(
-          regional_catalog_, uuid);
-      if (catalog_entry != regional_catalog_.end()) {
-        auto regional_service = AdBlockRegionalServiceFactory(
-            *catalog_entry, delegate_,
-            base::BindRepeating(&AdBlockRegionalServiceManager::AddResources,
-                                base::Unretained(this)));
-        regional_service->Start();
-        regional_services_.insert(
-            std::make_pair(uuid, std::move(regional_service)));
+      auto catalog_entry =
+          brave_shields::FindAdBlockFilterListByUUID(regional_catalog_, uuid);
+      auto existing_engine = regional_services_.find(uuid);
+      // Iterating through locally enabled lists - don't disable any engines or
+      // update existing engines with a potentially new catalog entry. They'll
+      // be handled after a browser restart.
+      if (catalog_entry != regional_catalog_.end() &&
+          existing_engine == regional_services_.end()) {
+        auto regional_filters_provider =
+            std::make_unique<AdBlockRegionalFiltersProvider>(
+                component_update_service_, *catalog_entry);
+        auto regional_service =
+            std::unique_ptr<AdBlockEngine, base::OnTaskRunnerDeleter>(
+                new AdBlockEngine(), base::OnTaskRunnerDeleter(task_runner_));
+        auto observer =
+            std::make_unique<AdBlockService::SourceProviderObserver>(
+                regional_service->AsWeakPtr(), regional_filters_provider.get(),
+                resource_provider_, task_runner_);
+        regional_services_.insert({uuid, std::move(regional_service)});
+        regional_filters_providers_.insert(
+            {uuid, std::move(regional_filters_provider)});
+        regional_source_observers_.insert({uuid, std::move(observer)});
       }
     }
   }
-
-  initialized_ = true;
 }
 
 void AdBlockRegionalServiceManager::UpdateFilterListPrefs(
     const std::string& uuid,
     bool enabled) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  PrefService* local_state = delegate_->local_state();
-  if (!local_state)
+  if (!local_state_)
     return;
-  DictionaryPrefUpdate update(local_state, prefs::kAdBlockRegionalFilters);
+  DictionaryPrefUpdate update(local_state_, prefs::kAdBlockRegionalFilters);
   base::Value* regional_filters_dict = update.Get();
   auto regional_filter_dict = base::Value(base::Value::Type::DICTIONARY);
   regional_filter_dict.SetBoolKey("enabled", enabled);
   regional_filters_dict->SetKey(uuid, std::move(regional_filter_dict));
 
   if (uuid == kCookieListUuid) {
-    local_state->SetBoolean(prefs::kAdBlockCookieListSettingTouched, true);
+    local_state_->SetBoolean(prefs::kAdBlockCookieListSettingTouched, true);
   }
 }
 
-bool AdBlockRegionalServiceManager::IsInitialized() const {
-  return initialized_;
-}
-
 bool AdBlockRegionalServiceManager::Start() {
-  base::AutoLock lock(regional_services_lock_);
-  for (const auto& regional_service : regional_services_) {
-    regional_service.second->Start();
-  }
-
   return true;
 }
 
@@ -148,9 +165,6 @@ void AdBlockRegionalServiceManager::ShouldStartRequest(
     bool* did_match_exception,
     bool* did_match_important,
     std::string* mock_data_url) {
-  if (!IsInitialized())
-    return;
-
   base::AutoLock lock(regional_services_lock_);
 
   for (const auto& regional_service : regional_services_) {
@@ -186,39 +200,50 @@ void AdBlockRegionalServiceManager::EnableTag(const std::string& tag,
   }
 }
 
-void AdBlockRegionalServiceManager::AddResources(
-    const std::string& resources) {
+void AdBlockRegionalServiceManager::AddResources(const std::string& resources) {
   base::AutoLock lock(regional_services_lock_);
   for (const auto& regional_service : regional_services_) {
     regional_service.second->AddResources(resources);
   }
 }
 
-void AdBlockRegionalServiceManager::EnableFilterList(
-    const std::string& uuid, bool enabled) {
+void AdBlockRegionalServiceManager::EnableFilterList(const std::string& uuid,
+                                                     bool enabled) {
   DCHECK(!uuid.empty());
-  auto catalog_entry = brave_shields::FindAdBlockFilterListByUUID(
-      regional_catalog_, uuid);
+  auto catalog_entry =
+      brave_shields::FindAdBlockFilterListByUUID(regional_catalog_, uuid);
 
   // Enable or disable the specified filter list
-  if (initialized_) {
-    base::AutoLock lock(regional_services_lock_);
-    DCHECK(catalog_entry != regional_catalog_.end());
-    auto it = regional_services_.find(uuid);
-    if (enabled) {
-      DCHECK(it == regional_services_.end());
-      auto regional_service = AdBlockRegionalServiceFactory(
-          *catalog_entry, delegate_,
-          base::BindRepeating(&AdBlockRegionalServiceManager::AddResources,
-                              base::Unretained(this)));
-      regional_service->Start();
-      regional_services_.insert(
-          std::make_pair(uuid, std::move(regional_service)));
-    } else {
-      DCHECK(it != regional_services_.end());
-      it->second->Unregister();
-      regional_services_.erase(it);
-    }
+  base::AutoLock lock(regional_services_lock_);
+  DCHECK(catalog_entry != regional_catalog_.end());
+  auto it = regional_services_.find(uuid);
+  if (enabled) {
+    DCHECK(it == regional_services_.end());
+    auto regional_filters_provider =
+        std::make_unique<AdBlockRegionalFiltersProvider>(
+            component_update_service_, *catalog_entry);
+    auto regional_service =
+        std::unique_ptr<AdBlockEngine, base::OnTaskRunnerDeleter>(
+            new AdBlockEngine(), base::OnTaskRunnerDeleter(task_runner_));
+    auto observer = std::make_unique<AdBlockService::SourceProviderObserver>(
+        regional_service->AsWeakPtr(), regional_filters_provider.get(),
+        resource_provider_, task_runner_);
+    regional_services_.insert({uuid, std::move(regional_service)});
+    regional_filters_providers_.insert(
+        {uuid, std::move(regional_filters_provider)});
+    regional_source_observers_.insert({uuid, std::move(observer)});
+  } else {
+    auto observer = regional_source_observers_.find(uuid);
+    DCHECK(observer != regional_source_observers_.end());
+    regional_source_observers_.erase(observer);
+
+    DCHECK(it != regional_services_.end());
+    regional_services_.erase(it);
+
+    auto it2 = regional_filters_providers_.find(uuid);
+    DCHECK(it2 != regional_filters_providers_.end());
+    std::move(*it2->second).Delete();
+    regional_filters_providers_.erase(it2);
   }
 
   // Update preferences to reflect enabled/disabled state of specified
@@ -226,7 +251,7 @@ void AdBlockRegionalServiceManager::EnableFilterList(
   base::PostTask(
       FROM_HERE, {content::BrowserThread::UI},
       base::BindOnce(&AdBlockRegionalServiceManager::UpdateFilterListPrefs,
-                     base::Unretained(this), uuid, enabled));
+                     weak_factory_.GetWeakPtr(), uuid, enabled));
 }
 
 absl::optional<base::Value> AdBlockRegionalServiceManager::UrlCosmeticResources(
@@ -239,7 +264,7 @@ absl::optional<base::Value> AdBlockRegionalServiceManager::UrlCosmeticResources(
   absl::optional<base::Value> first_value =
       it->second->UrlCosmeticResources(url);
 
-  for ( ; it != regional_services_.end(); it++) {
+  for (; it != regional_services_.end(); it++) {
     absl::optional<base::Value> next_value =
         it->second->UrlCosmeticResources(url);
     if (first_value) {
@@ -277,18 +302,9 @@ base::Value AdBlockRegionalServiceManager::HiddenClassIdSelectors(
 }
 
 void AdBlockRegionalServiceManager::SetRegionalCatalog(
-        std::vector<adblock::FilterList> catalog) {
+    std::vector<adblock::FilterList> catalog) {
   regional_catalog_ = std::move(catalog);
-  for (const auto& regional_service : regional_services_) {
-    auto catalog_entry = brave_shields::FindAdBlockFilterListByUUID(
-        regional_catalog_, regional_service.second->GetUUID());
-    if (catalog_entry != regional_catalog_.end()) {
-      regional_service.second->SetCatalogEntry(*catalog_entry);
-    }
-  }
-  if (!initialized_) {
-    StartRegionalServices();
-  }
+  StartRegionalServices();
 }
 
 const std::vector<adblock::FilterList>&
@@ -299,15 +315,14 @@ AdBlockRegionalServiceManager::GetRegionalCatalog() {
 std::unique_ptr<base::ListValue>
 AdBlockRegionalServiceManager::GetRegionalLists() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  PrefService* local_state = delegate_->local_state();
-  if (!local_state)
+  if (!local_state_)
     return nullptr;
   const base::DictionaryValue* regional_filters_dict =
       &base::Value::AsDictionaryValue(
-          *local_state->GetDictionary(prefs::kAdBlockRegionalFilters));
+          *local_state_->GetDictionary(prefs::kAdBlockRegionalFilters));
 
   const bool cookie_list_touched =
-      local_state->GetBoolean(prefs::kAdBlockCookieListSettingTouched);
+      local_state_->GetBoolean(prefs::kAdBlockCookieListSettingTouched);
 
   auto list_value = std::make_unique<base::ListValue>();
   for (const auto& region_list : regional_catalog_) {
@@ -341,11 +356,21 @@ AdBlockRegionalServiceManager::GetRegionalLists() {
   return list_value;
 }
 
+void AdBlockRegionalServiceManager::OnRegionalCatalogLoaded(
+    const std::string& catalog_json) {
+  SetRegionalCatalog(RegionalCatalogFromJSON(catalog_json));
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 std::unique_ptr<AdBlockRegionalServiceManager>
-AdBlockRegionalServiceManagerFactory(BraveComponent::Delegate* delegate) {
-  return std::make_unique<AdBlockRegionalServiceManager>(delegate);
+AdBlockRegionalServiceManagerFactory(
+    PrefService* local_state,
+    std::string locale,
+    component_updater::ComponentUpdateService* cus,
+    scoped_refptr<base::SequencedTaskRunner> task_runner) {
+  return std::make_unique<AdBlockRegionalServiceManager>(local_state, locale,
+                                                         cus, task_runner);
 }
 
 }  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_regional_service_manager.h b/components/brave_shields/browser/ad_block_regional_service_manager.h
index 3a5db0999542..35965515c14e 100644
--- a/components/brave_shields/browser/ad_block_regional_service_manager.h
+++ b/components/brave_shields/browser/ad_block_regional_service_manager.h
@@ -17,6 +17,11 @@
 #include "base/values.h"
 #include "brave/components/adblock_rust_ffi/src/wrapper.h"
 #include "brave/components/brave_component_updater/browser/brave_component.h"
+#include "brave/components/brave_shields/browser/ad_block_engine.h"
+#include "brave/components/brave_shields/browser/ad_block_regional_catalog_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_regional_filters_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_resource_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "third_party/abseil-cpp/absl/types/optional.h"
 #include "third_party/blink/public/mojom/loader/resource_load_info.mojom-shared.h"
 #include "url/gurl.h"
@@ -35,20 +40,24 @@ class AdBlockRegionalService;
 
 // The AdBlock regional service manager, in charge of initializing and
 // managing regional AdBlock clients.
-class AdBlockRegionalServiceManager {
+class AdBlockRegionalServiceManager
+    : public AdBlockRegionalCatalogProvider::Observer {
  public:
-  explicit AdBlockRegionalServiceManager(BraveComponent::Delegate* delegate);
+  explicit AdBlockRegionalServiceManager(
+      PrefService* local_state,
+      std::string locale,
+      component_updater::ComponentUpdateService* cus,
+      scoped_refptr<base::SequencedTaskRunner> task_runner);
   AdBlockRegionalServiceManager(const AdBlockRegionalServiceManager&) = delete;
   AdBlockRegionalServiceManager& operator=(
       const AdBlockRegionalServiceManager&) = delete;
-  ~AdBlockRegionalServiceManager();
+  ~AdBlockRegionalServiceManager() override;
 
   std::unique_ptr<base::ListValue> GetRegionalLists();
 
   void SetRegionalCatalog(std::vector<adblock::FilterList> catalog);
   const std::vector<adblock::FilterList>& GetRegionalCatalog();
 
-  bool IsInitialized() const;
   bool Start();
   void ShouldStartRequest(const GURL& url,
                           blink::mojom::ResourceType resource_type,
@@ -72,24 +81,46 @@ class AdBlockRegionalServiceManager {
       const std::vector<std::string>& ids,
       const std::vector<std::string>& exceptions);
 
+  void Init(AdBlockResourceProvider* resource_provider,
+            AdBlockRegionalCatalogProvider* catalog_provider);
+
+  // AdBlockRegionalCatalogProvider::Observer
+  void OnRegionalCatalogLoaded(const std::string& catalog_json) override;
+
  private:
   friend class ::AdBlockServiceTest;
   void StartRegionalServices();
   void UpdateFilterListPrefs(const std::string& uuid, bool enabled);
 
-  raw_ptr<brave_component_updater::BraveComponent::Delegate> delegate_ =
-      nullptr;  // NOT OWNED
+  raw_ptr<PrefService> local_state_;
+  std::string locale_;
   bool initialized_;
   base::Lock regional_services_lock_;
-  std::map<std::string, std::unique_ptr<AdBlockRegionalService>>
+  std::map<std::string,
+           std::unique_ptr<AdBlockEngine, base::OnTaskRunnerDeleter>>
       regional_services_;
+  std::map<std::string, std::unique_ptr<AdBlockRegionalFiltersProvider>>
+      regional_filters_providers_;
+  std::map<std::string, std::unique_ptr<AdBlockService::SourceProviderObserver>>
+      regional_source_observers_;
 
   std::vector<adblock::FilterList> regional_catalog_;
+
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+  raw_ptr<component_updater::ComponentUpdateService> component_update_service_;
+  raw_ptr<AdBlockResourceProvider> resource_provider_;
+  raw_ptr<AdBlockRegionalCatalogProvider> catalog_provider_;
+
+  base::WeakPtrFactory<AdBlockRegionalServiceManager> weak_factory_{this};
 };
 
 // Creates the AdBlockRegionalServiceManager
 std::unique_ptr<AdBlockRegionalServiceManager>
-AdBlockRegionalServiceManagerFactory(BraveComponent::Delegate* delegate);
+AdBlockRegionalServiceManagerFactory(
+    PrefService* local_state,
+    std::string locale,
+    component_updater::ComponentUpdateService* cus,
+    scoped_refptr<base::SequencedTaskRunner> task_runner);
 
 }  // namespace brave_shields
 
diff --git a/components/brave_shields/browser/ad_block_resource_provider.cc b/components/brave_shields/browser/ad_block_resource_provider.cc
new file mode 100644
index 000000000000..7c1b94a56fc5
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_resource_provider.cc
@@ -0,0 +1,35 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "brave/components/brave_shields/browser/ad_block_resource_provider.h"
+
+#include <string>
+
+namespace brave_shields {
+
+AdBlockResourceProvider::AdBlockResourceProvider() {}
+
+AdBlockResourceProvider::~AdBlockResourceProvider() {}
+
+void AdBlockResourceProvider::AddObserver(
+    AdBlockResourceProvider::Observer* observer) {
+  if (!observers_.HasObserver(observer))
+    observers_.AddObserver(observer);
+}
+
+void AdBlockResourceProvider::RemoveObserver(
+    AdBlockResourceProvider::Observer* observer) {
+  if (observers_.HasObserver(observer))
+    observers_.RemoveObserver(observer);
+}
+
+void AdBlockResourceProvider::OnResourcesLoaded(
+    const std::string& resources_json) {
+  for (auto& observer : observers_) {
+    observer.OnResourcesLoaded(resources_json);
+  }
+}
+
+}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_resource_provider.h b/components/brave_shields/browser/ad_block_resource_provider.h
new file mode 100644
index 000000000000..be726faed78f
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_resource_provider.h
@@ -0,0 +1,47 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_RESOURCE_PROVIDER_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_RESOURCE_PROVIDER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/observer_list.h"
+#include "brave/components/brave_component_updater/browser/dat_file_util.h"
+#include "third_party/abseil-cpp/absl/types/optional.h"
+
+using brave_component_updater::DATFileDataBuffer;
+
+namespace brave_shields {
+
+// Interface for any source that can load resource replacements into an adblock
+// engine.
+class AdBlockResourceProvider {
+ public:
+  class Observer : public base::CheckedObserver {
+   public:
+    virtual void OnResourcesLoaded(const std::string& resources_json) = 0;
+  };
+
+  AdBlockResourceProvider();
+  virtual ~AdBlockResourceProvider();
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  virtual void LoadResources(
+      base::OnceCallback<void(const std::string& resources_json)>) = 0;
+
+ protected:
+  void OnResourcesLoaded(const std::string& resources_json);
+
+ private:
+  base::ObserverList<Observer> observers_;
+};
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_RESOURCE_PROVIDER_H_
diff --git a/components/brave_shields/browser/ad_block_service.cc b/components/brave_shields/browser/ad_block_service.cc
index 03cebf45b42d..98f02784d9d2 100644
--- a/components/brave_shields/browser/ad_block_service.cc
+++ b/components/brave_shields/browser/ad_block_service.cc
@@ -18,7 +18,9 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_restrictions.h"
 #include "brave/components/adblock_rust_ffi/src/wrapper.h"
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
+#include "brave/components/brave_shields/browser/ad_block_custom_filters_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_default_filters_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_engine.h"
 #include "brave/components/brave_shields/browser/ad_block_regional_service_manager.h"
 #include "brave/components/brave_shields/browser/ad_block_service_helper.h"
 #include "brave/components/brave_shields/browser/ad_block_subscription_service_manager.h"
@@ -33,7 +35,6 @@
 #include "url/origin.h"
 
 #define DAT_FILE "rs-ABPFilterParserData.dat"
-#define REGIONAL_CATALOG "regional_catalog.json"
 
 namespace brave_shields {
 
@@ -59,9 +60,48 @@ void AdBlockServiceDomainResolver(const char* host,
 
 }  // namespace
 
-std::string AdBlockService::g_ad_block_component_id_(kAdBlockComponentId);
-std::string AdBlockService::g_ad_block_component_base64_public_key_(
-    kAdBlockComponentBase64PublicKey);
+AdBlockService::SourceProviderObserver::SourceProviderObserver(
+    base::WeakPtr<AdBlockEngine> adblock_engine,
+    AdBlockFiltersProvider* filters_provider,
+    AdBlockResourceProvider* resource_provider,
+    scoped_refptr<base::SequencedTaskRunner> task_runner)
+    : adblock_engine_(adblock_engine),
+      filters_provider_(filters_provider),
+      resource_provider_(resource_provider),
+      task_runner_(task_runner) {
+  filters_provider_->AddObserver(this);
+  filters_provider_->LoadDAT(this);
+}
+
+AdBlockService::SourceProviderObserver::~SourceProviderObserver() {
+  filters_provider_->RemoveObserver(this);
+  resource_provider_->RemoveObserver(this);
+}
+
+void AdBlockService::SourceProviderObserver::OnDATLoaded(
+    bool deserialize,
+    const DATFileDataBuffer& dat_buf) {
+  deserialize_ = deserialize;
+  dat_buf_ = std::move(dat_buf);
+  // multiple AddObserver calls are ignored
+  resource_provider_->AddObserver(this);
+  resource_provider_->LoadResources(base::BindOnce(
+      &SourceProviderObserver::OnResourcesLoaded, weak_factory_.GetWeakPtr()));
+}
+
+void AdBlockService::SourceProviderObserver::OnResourcesLoaded(
+    const std::string& resources_json) {
+  if (dat_buf_.empty()) {
+    task_runner_->PostTask(
+        FROM_HERE, base::BindOnce(&AdBlockEngine::AddResources, adblock_engine_,
+                                  resources_json));
+  } else {
+    task_runner_->PostTask(
+        FROM_HERE,
+        base::BindOnce(&AdBlockEngine::Load, adblock_engine_, deserialize_,
+                       std::move(dat_buf_), resources_json));
+  }
+}
 
 void AdBlockService::ShouldStartRequest(
     const GURL& url,
@@ -72,16 +112,14 @@ void AdBlockService::ShouldStartRequest(
     bool* did_match_exception,
     bool* did_match_important,
     std::string* mock_data_url) {
-  if (!IsInitialized())
-    return;
-
+  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
   if (aggressive_blocking ||
       base::FeatureList::IsEnabled(
           brave_shields::features::kBraveAdblockDefault1pBlocking) ||
       !SameDomainOrHost(
           url, url::Origin::CreateFromNormalizedTuple("https", tab_host, 80),
           net::registry_controlled_domains::INCLUDE_PRIVATE_REGISTRIES)) {
-    AdBlockBaseService::ShouldStartRequest(
+    default_service()->ShouldStartRequest(
         url, resource_type, tab_host, aggressive_blocking, did_match_rule,
         did_match_exception, did_match_important, mock_data_url);
     if (did_match_important && *did_match_important) {
@@ -112,8 +150,9 @@ absl::optional<std::string> AdBlockService::GetCspDirectives(
     const GURL& url,
     blink::mojom::ResourceType resource_type,
     const std::string& tab_host) {
+  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
   auto csp_directives =
-      AdBlockBaseService::GetCspDirectives(url, resource_type, tab_host);
+      default_service()->GetCspDirectives(url, resource_type, tab_host);
 
   const auto regional_csp = regional_service_manager()->GetCspDirectives(
       url, resource_type, tab_host);
@@ -128,8 +167,9 @@ absl::optional<std::string> AdBlockService::GetCspDirectives(
 
 absl::optional<base::Value> AdBlockService::UrlCosmeticResources(
     const std::string& url) {
+  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
   absl::optional<base::Value> resources =
-      AdBlockBaseService::UrlCosmeticResources(url);
+      default_service()->UrlCosmeticResources(url);
 
   if (!resources || !resources->is_dict()) {
     return resources;
@@ -175,8 +215,9 @@ base::Value AdBlockService::HiddenClassIdSelectors(
     const std::vector<std::string>& classes,
     const std::vector<std::string>& ids,
     const std::vector<std::string>& exceptions) {
+  DCHECK(GetTaskRunner()->RunsTasksInCurrentSequence());
   base::Value hide_selectors =
-      AdBlockBaseService::HiddenClassIdSelectors(classes, ids, exceptions);
+      default_service()->HiddenClassIdSelectors(classes, ids, exceptions);
 
   base::Value regional_selectors =
       regional_service_manager()->HiddenClassIdSelectors(classes, ids,
@@ -212,95 +253,101 @@ base::Value AdBlockService::HiddenClassIdSelectors(
 }
 
 AdBlockRegionalServiceManager* AdBlockService::regional_service_manager() {
-  if (!regional_service_manager_)
+  if (!regional_service_manager_) {
     regional_service_manager_ =
         brave_shields::AdBlockRegionalServiceManagerFactory(
-            component_delegate_);
+            local_state_, locale_, component_update_service_, GetTaskRunner());
+    regional_service_manager_->Init(default_filters_provider_.get(),
+                                    default_filters_provider_.get());
+  }
   return regional_service_manager_.get();
 }
 
-brave_shields::AdBlockCustomFiltersService*
-AdBlockService::custom_filters_service() {
-  if (!custom_filters_service_)
+AdBlockEngine* AdBlockService::default_service() {
+  if (!default_service_) {
+    default_service_ =
+        std::unique_ptr<AdBlockEngine, base::OnTaskRunnerDeleter>(
+            new AdBlockEngine(), base::OnTaskRunnerDeleter(GetTaskRunner()));
+    default_service_observer_ = std::make_unique<SourceProviderObserver>(
+        default_service_->AsWeakPtr(), default_filters_provider_.get(),
+        default_filters_provider_.get(), GetTaskRunner());
+  }
+  return default_service_.get();
+}
+
+AdBlockEngine* AdBlockService::custom_filters_service() {
+  if (!custom_filters_service_) {
     custom_filters_service_ =
-        brave_shields::AdBlockCustomFiltersServiceFactory(component_delegate_);
+        std::unique_ptr<AdBlockEngine, base::OnTaskRunnerDeleter>(
+            new AdBlockEngine(), base::OnTaskRunnerDeleter(GetTaskRunner()));
+    custom_filters_service_observer_ = std::make_unique<SourceProviderObserver>(
+        custom_filters_service_->AsWeakPtr(), custom_filters_provider_.get(),
+        default_filters_provider_.get(), GetTaskRunner());
+  }
   return custom_filters_service_.get();
 }
 
+brave_shields::AdBlockCustomFiltersProvider*
+AdBlockService::custom_filters_provider() {
+  return custom_filters_provider_.get();
+}
+
 brave_shields::AdBlockSubscriptionServiceManager*
 AdBlockService::subscription_service_manager() {
+  if (!subscription_service_manager_->IsInitialized()) {
+    subscription_service_manager_->Init(default_filters_provider_.get());
+  }
   return subscription_service_manager_.get();
 }
 
 AdBlockService::AdBlockService(
-    brave_component_updater::BraveComponent::Delegate* delegate,
+    PrefService* local_state,
+    std::string locale,
+    component_updater::ComponentUpdateService* cus,
+    scoped_refptr<base::SequencedTaskRunner> task_runner,
     std::unique_ptr<AdBlockSubscriptionServiceManager>
         subscription_service_manager)
-    : AdBlockBaseService(delegate),
-      component_delegate_(delegate),
-      subscription_service_manager_(std::move(subscription_service_manager)) {}
+    : local_state_(local_state),
+      locale_(locale),
+      component_update_service_(cus),
+      task_runner_(task_runner),
+      custom_filters_service_(nullptr, base::OnTaskRunnerDeleter(task_runner_)),
+      default_service_(nullptr, base::OnTaskRunnerDeleter(task_runner_)),
+      subscription_service_manager_(std::move(subscription_service_manager)) {
+  default_filters_provider_ =
+      std::make_unique<brave_shields::AdBlockDefaultFiltersProvider>(
+          component_update_service_);
+  custom_filters_provider_ =
+      std::make_unique<brave_shields::AdBlockCustomFiltersProvider>(
+          local_state_);
+}
 
 AdBlockService::~AdBlockService() {}
 
-bool AdBlockService::Init() {
+bool AdBlockService::Start() {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   // Initializes adblock-rust's domain resolution implementation
   adblock::SetDomainResolver(AdBlockServiceDomainResolver);
 
-  if (!AdBlockBaseService::Init())
-    return false;
+  // Initialize each service:
+  default_service();
+  custom_filters_service();
+  regional_service_manager();
+  subscription_service_manager();
 
-  Register(kAdBlockComponentName, g_ad_block_component_id_,
-           g_ad_block_component_base64_public_key_);
   return true;
 }
 
-void AdBlockService::OnComponentReady(const std::string& component_id,
-                                      const base::FilePath& install_dir,
-                                      const std::string& manifest) {
-  // Regional service manager depends on regional catalog loading
-  custom_filters_service()->Start();
-  subscription_service_manager()->Start();
-
-  base::FilePath dat_file_path = install_dir.AppendASCII(DAT_FILE);
-  GetDATFileData(dat_file_path);
-
-  base::FilePath regional_catalog_file_path =
-      install_dir.AppendASCII(REGIONAL_CATALOG);
-
-  base::FilePath resources_file_path =
-      install_dir.AppendASCII(kAdBlockResourcesFilename);
-  base::PostTaskAndReplyWithResult(
-      GetTaskRunner().get(), FROM_HERE,
-      base::BindOnce(&brave_component_updater::GetDATFileAsString,
-                     resources_file_path),
-      base::BindOnce(&AdBlockService::OnResourcesFileDataReady,
-                     weak_factory_.GetWeakPtr()));
-  base::PostTaskAndReplyWithResult(
-      GetTaskRunner().get(), FROM_HERE,
-      base::BindOnce(&brave_component_updater::GetDATFileAsString,
-                     regional_catalog_file_path),
-      base::BindOnce(&AdBlockService::OnRegionalCatalogFileDataReady,
-                     weak_factory_.GetWeakPtr()));
-}
-
-void AdBlockService::OnResourcesFileDataReady(const std::string& resources) {
-  AddResources(resources);
-  custom_filters_service()->AddResources(resources);
-}
-
-void AdBlockService::OnRegionalCatalogFileDataReady(
-    const std::string& catalog_json) {
-  regional_service_manager()->SetRegionalCatalog(
-      RegionalCatalogFromJSON(catalog_json));
-  regional_service_manager()->Start();
+void AdBlockService::EnableTag(const std::string& tag, bool enabled) {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  // Tags only need to be modified for the default engine.
+  GetTaskRunner()->PostTask(
+      FROM_HERE, base::BindOnce(&AdBlockEngine::EnableTag,
+                                default_service()->AsWeakPtr(), tag, enabled));
 }
 
-// static
-void AdBlockService::SetComponentIdAndBase64PublicKeyForTest(
-    const std::string& component_id,
-    const std::string& component_base64_public_key) {
-  g_ad_block_component_id_ = component_id;
-  g_ad_block_component_base64_public_key_ = component_base64_public_key;
+base::SequencedTaskRunner* AdBlockService::GetTaskRunner() {
+  return task_runner_.get();
 }
 
 void RegisterPrefsForAdBlockService(PrefRegistrySimple* registry) {
@@ -311,4 +358,28 @@ void RegisterPrefsForAdBlockService(PrefRegistrySimple* registry) {
   registry->RegisterBooleanPref(prefs::kAdBlockCheckedDefaultRegion, false);
 }
 
+AdBlockResourceProvider* AdBlockService::resource_provider() {
+  return default_filters_provider_.get();
+}
+
+void AdBlockService::UseSourceProvidersForTest(
+    AdBlockFiltersProvider* source_provider,
+    AdBlockResourceProvider* resource_provider) {
+  default_service_observer_ = std::make_unique<SourceProviderObserver>(
+      default_service_->AsWeakPtr(), source_provider, resource_provider,
+      GetTaskRunner());
+}
+
+void AdBlockService::UseCustomSourceProvidersForTest(
+    AdBlockFiltersProvider* source_provider,
+    AdBlockResourceProvider* resource_provider) {
+  custom_filters_service_observer_ = std::make_unique<SourceProviderObserver>(
+      custom_filters_service_->AsWeakPtr(), source_provider, resource_provider,
+      GetTaskRunner());
+}
+
+bool AdBlockService::TagExistsForTest(const std::string& tag) {
+  return default_service()->TagExists(tag);
+}
+
 }  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_service.h b/components/brave_shields/browser/ad_block_service.h
index c2f3c206c3f9..cd9d29180dce 100644
--- a/components/brave_shields/browser/ad_block_service.h
+++ b/components/brave_shields/browser/ad_block_service.h
@@ -13,47 +13,82 @@
 #include <vector>
 
 #include "base/memory/raw_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/sequence_checker.h"
+#include "base/task/sequenced_task_runner.h"
 #include "base/values.h"
-#include "brave/components/brave_shields/browser/ad_block_base_service.h"
+#include "brave/components/brave_shields/browser/ad_block_filters_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_resource_provider.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "content/public/browser/browser_thread.h"
 #include "third_party/abseil-cpp/absl/types/optional.h"
+#include "third_party/blink/public/mojom/loader/resource_load_info.mojom-shared.h"
+#include "url/gurl.h"
 
 class AdBlockServiceTest;
+class BraveAdBlockTPNetworkDelegateHelperTest;
 class DomainBlockTest;
+class EphemeralStorage1pDomainBlockBrowserTest;
+class PerfPredictorTabHelperTest;
 class PrefChangeRegistrar;
 class PrefService;
 
-using brave_component_updater::BraveComponent;
+namespace component_updater {
+class ComponentUpdateService;
+}  // namespace component_updater
 
 namespace brave_shields {
 
+class AdBlockEngine;
+class AdBlockDefaultFiltersProvider;
 class AdBlockRegionalServiceManager;
-class AdBlockCustomFiltersService;
+class AdBlockCustomFiltersProvider;
+class AdBlockRegionalCatalogProvider;
 class AdBlockSubscriptionServiceManager;
 
-const char kAdBlockResourcesFilename[] = "resources.json";
-const char kAdBlockComponentName[] = "Brave Ad Block Updater";
-const char kAdBlockComponentId[] = "cffkpbalmllkdoenhmdmpbkajipdjfam";
-const char kAdBlockComponentBase64PublicKey[] =
-    "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAs0qzJmHSgIiw7IGFCxij"
-    "1NnB5hJ5ZQ1LKW9htL4EBOaMJvmqaDs/wfq0nw/goBHWsqqkMBynRTu2Hxxirvdb"
-    "cugn1Goys5QKPgAvKwDHJp9jlnADWm5xQvPQ4GE1mK1/I3ka9cEOCzPW6GI+wGLi"
-    "VPx9VZrxHHsSBIJRaEB5Tyi5bj0CZ+kcfMnRTsXIBw3C6xJgCVKISQUkd8mawVvG"
-    "vqOhBOogCdb9qza5eJ1Cgx8RWKucFfaWWxKLOelCiBMT1Hm1znAoVBHG/blhJJOD"
-    "5HcH/heRrB4MvrE1J76WF3fvZ03aHVcnlLtQeiNNOZ7VbBDXdie8Nomf/QswbBGa"
-    "VwIDAQAB";
-
 // The brave shields service in charge of ad-block checking and init.
-class AdBlockService : public AdBlockBaseService {
+class AdBlockService {
  public:
+  class SourceProviderObserver : public AdBlockResourceProvider::Observer,
+                                 public AdBlockFiltersProvider::Observer {
+   public:
+    SourceProviderObserver(
+        base::WeakPtr<AdBlockEngine> adblock_engine,
+        AdBlockFiltersProvider* source_provider,
+        AdBlockResourceProvider* resource_provider,
+        scoped_refptr<base::SequencedTaskRunner> task_runner);
+    SourceProviderObserver(const SourceProviderObserver&) = delete;
+    SourceProviderObserver& operator=(const SourceProviderObserver&) = delete;
+    ~SourceProviderObserver() override;
+
+   private:
+    // AdBlockFiltersProvider::Observer
+    void OnDATLoaded(bool deserialize,
+                     const DATFileDataBuffer& dat_buf) override;
+
+    // AdBlockResourceProvider::Observer
+    void OnResourcesLoaded(const std::string& resources_json) override;
+
+    bool deserialize_;
+    DATFileDataBuffer dat_buf_;
+    base::WeakPtr<AdBlockEngine> adblock_engine_;
+    raw_ptr<AdBlockFiltersProvider> filters_provider_;    // not owned
+    raw_ptr<AdBlockResourceProvider> resource_provider_;  // not owned
+    scoped_refptr<base::SequencedTaskRunner> task_runner_;
+
+    base::WeakPtrFactory<SourceProviderObserver> weak_factory_{this};
+  };
+
   explicit AdBlockService(
-      BraveComponent::Delegate* delegate,
+      PrefService* local_state,
+      std::string locale,
+      component_updater::ComponentUpdateService* cus,
+      scoped_refptr<base::SequencedTaskRunner> task_runner,
       std::unique_ptr<AdBlockSubscriptionServiceManager> manager);
   AdBlockService(const AdBlockService&) = delete;
   AdBlockService& operator=(const AdBlockService&) = delete;
-  ~AdBlockService() override;
+  ~AdBlockService();
 
   void ShouldStartRequest(const GURL& url,
                           blink::mojom::ResourceType resource_type,
@@ -62,49 +97,74 @@ class AdBlockService : public AdBlockBaseService {
                           bool* did_match_rule,
                           bool* did_match_exception,
                           bool* did_match_important,
-                          std::string* mock_data_url) override;
+                          std::string* mock_data_url);
   absl::optional<std::string> GetCspDirectives(
       const GURL& url,
       blink::mojom::ResourceType resource_type,
       const std::string& tab_host);
-  absl::optional<base::Value> UrlCosmeticResources(
-      const std::string& url) override;
+  absl::optional<base::Value> UrlCosmeticResources(const std::string& url);
   base::Value HiddenClassIdSelectors(
       const std::vector<std::string>& classes,
       const std::vector<std::string>& ids,
-      const std::vector<std::string>& exceptions) override;
+      const std::vector<std::string>& exceptions);
 
   AdBlockRegionalServiceManager* regional_service_manager();
-  AdBlockCustomFiltersService* custom_filters_service();
+  AdBlockEngine* custom_filters_service();
+  AdBlockEngine* default_service();
   AdBlockSubscriptionServiceManager* subscription_service_manager();
 
- protected:
-  bool Init() override;
-  void OnComponentReady(const std::string& component_id,
-                        const base::FilePath& install_dir,
-                        const std::string& manifest) override;
-  void OnResourcesFileDataReady(const std::string& resources);
-  void OnRegionalCatalogFileDataReady(const std::string& catalog_json);
+  AdBlockCustomFiltersProvider* custom_filters_provider();
+
+  void EnableTag(const std::string& tag, bool enabled);
+
+  base::SequencedTaskRunner* GetTaskRunner();
+
+  bool Start();
 
  private:
+  friend class ::BraveAdBlockTPNetworkDelegateHelperTest;
   friend class ::AdBlockServiceTest;
   friend class ::DomainBlockTest;
-  static std::string g_ad_block_component_id_;
-  static std::string g_ad_block_component_base64_public_key_;
+  friend class ::EphemeralStorage1pDomainBlockBrowserTest;
+  friend class ::PerfPredictorTabHelperTest;
+
   static std::string g_ad_block_dat_file_version_;
-  static void SetComponentIdAndBase64PublicKeyForTest(
-      const std::string& component_id,
-      const std::string& component_base64_public_key);
 
-  raw_ptr<BraveComponent::Delegate> component_delegate_ = nullptr;
+  AdBlockResourceProvider* resource_provider();
+
+  void UseSourceProvidersForTest(AdBlockFiltersProvider* source_provider,
+                                 AdBlockResourceProvider* resource_provider);
+  void UseCustomSourceProvidersForTest(
+      AdBlockFiltersProvider* source_provider,
+      AdBlockResourceProvider* resource_provider);
+  bool TagExistsForTest(const std::string& tag);
+
+  raw_ptr<PrefService> local_state_;
+  std::string locale_;
+
+  raw_ptr<component_updater::ComponentUpdateService> component_update_service_;
+
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
 
   std::unique_ptr<brave_shields::AdBlockRegionalServiceManager>
       regional_service_manager_;
-  std::unique_ptr<brave_shields::AdBlockCustomFiltersService>
+  std::unique_ptr<brave_shields::AdBlockEngine, base::OnTaskRunnerDeleter>
       custom_filters_service_;
+  std::unique_ptr<brave_shields::AdBlockEngine, base::OnTaskRunnerDeleter>
+      default_service_;
   std::unique_ptr<brave_shields::AdBlockSubscriptionServiceManager>
       subscription_service_manager_;
 
+  std::unique_ptr<brave_shields::AdBlockCustomFiltersProvider>
+      custom_filters_provider_;
+  std::unique_ptr<brave_shields::AdBlockDefaultFiltersProvider>
+      default_filters_provider_;
+
+  std::unique_ptr<SourceProviderObserver> default_service_observer_;
+  std::unique_ptr<SourceProviderObserver> custom_filters_service_observer_;
+
+  SEQUENCE_CHECKER(sequence_checker_);
+
   base::WeakPtrFactory<AdBlockService> weak_factory_{this};
 };
 
diff --git a/components/brave_shields/browser/ad_block_subscription_filters_provider.cc b/components/brave_shields/browser/ad_block_subscription_filters_provider.cc
new file mode 100644
index 000000000000..537feb9b1602
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_subscription_filters_provider.cc
@@ -0,0 +1,35 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "brave/components/brave_shields/browser/ad_block_subscription_filters_provider.h"
+
+#include <utility>
+
+#include "base/logging.h"
+#include "base/task/thread_pool.h"
+#include "brave/components/brave_shields/common/pref_names.h"
+#include "components/prefs/pref_service.h"
+#include "content/public/browser/browser_task_traits.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace brave_shields {
+
+AdBlockSubscriptionFiltersProvider::AdBlockSubscriptionFiltersProvider(
+    PrefService* local_state,
+    base::FilePath list_file)
+    : list_file_(list_file) {}
+
+AdBlockSubscriptionFiltersProvider::~AdBlockSubscriptionFiltersProvider() {}
+
+void AdBlockSubscriptionFiltersProvider::LoadDATBuffer(
+    base::OnceCallback<void(bool deserialize, const DATFileDataBuffer& dat_buf)>
+        cb) {
+  base::ThreadPool::PostTaskAndReplyWithResult(
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&brave_component_updater::ReadDATFileData, list_file_),
+      base::BindOnce(std::move(cb), false));
+}
+
+}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_subscription_filters_provider.h b/components/brave_shields/browser/ad_block_subscription_filters_provider.h
new file mode 100644
index 000000000000..7b6a34e30553
--- /dev/null
+++ b/components/brave_shields/browser/ad_block_subscription_filters_provider.h
@@ -0,0 +1,42 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_SUBSCRIPTION_FILTERS_PROVIDER_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_SUBSCRIPTION_FILTERS_PROVIDER_H_
+
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "brave/components/brave_component_updater/browser/dat_file_util.h"
+#include "brave/components/brave_shields/browser/ad_block_filters_provider.h"
+
+using brave_component_updater::DATFileDataBuffer;
+
+class PrefService;
+
+namespace brave_shields {
+
+class AdBlockSubscriptionFiltersProvider : public AdBlockFiltersProvider {
+ public:
+  AdBlockSubscriptionFiltersProvider(PrefService* local_state,
+                                     base::FilePath list_file);
+  AdBlockSubscriptionFiltersProvider(
+      const AdBlockSubscriptionFiltersProvider&) = delete;
+  AdBlockSubscriptionFiltersProvider& operator=(
+      const AdBlockSubscriptionFiltersProvider&) = delete;
+  ~AdBlockSubscriptionFiltersProvider() override;
+
+  void LoadDATBuffer(
+      base::OnceCallback<void(bool deserialize,
+                              const DATFileDataBuffer& dat_buf)>) override;
+
+ private:
+  base::FilePath list_file_;
+
+  base::WeakPtrFactory<AdBlockSubscriptionFiltersProvider> weak_factory_{this};
+};
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_SUBSCRIPTION_FILTERS_PROVIDER_H_
diff --git a/components/brave_shields/browser/ad_block_subscription_service.cc b/components/brave_shields/browser/ad_block_subscription_service.cc
deleted file mode 100644
index f5fba60718b5..000000000000
--- a/components/brave_shields/browser/ad_block_subscription_service.cc
+++ /dev/null
@@ -1,88 +0,0 @@
-/* Copyright (c) 2021 The Brave Authors. All rights reserved.
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#include "brave/components/brave_shields/browser/ad_block_subscription_service.h"
-
-#include "base/files/file_path.h"
-#include "base/json/json_value_converter.h"
-#include "base/json/values_util.h"
-#include "base/logging.h"
-#include "base/strings/string_piece.h"
-#include "brave/components/brave_shields/browser/ad_block_service.h"
-#include "brave/components/brave_shields/browser/ad_block_service_helper.h"
-#include "brave/components/brave_shields/common/brave_shield_constants.h"
-
-namespace brave_shields {
-
-namespace {
-bool SkipGURLField(base::StringPiece value, GURL* field) {
-  return true;
-}
-
-bool ParseTimeValue(const base::Value* value, base::Time* field) {
-  auto time = base::ValueToTime(value);
-  if (!time) {
-    return false;
-  }
-  *field = *time;
-  return true;
-}
-}  // namespace
-
-void SubscriptionInfo::RegisterJSONConverter(
-    base::JSONValueConverter<SubscriptionInfo>* converter) {
-  // The `subscription_url` field is skipped, as it's not stored within the
-  // JSON value and should be populated externally.
-  converter->RegisterCustomField<GURL>(
-      "subscription_url", &SubscriptionInfo::subscription_url, &SkipGURLField);
-  converter->RegisterCustomValueField<base::Time>(
-      "last_update_attempt", &SubscriptionInfo::last_update_attempt,
-      &ParseTimeValue);
-  converter->RegisterCustomValueField<base::Time>(
-      "last_successful_update_attempt",
-      &SubscriptionInfo::last_successful_update_attempt, &ParseTimeValue);
-  converter->RegisterBoolField("enabled", &SubscriptionInfo::enabled);
-}
-
-AdBlockSubscriptionService::AdBlockSubscriptionService(
-    const SubscriptionInfo& info,
-    const base::FilePath list_file,
-    brave_component_updater::BraveComponent::Delegate* delegate)
-    : AdBlockBaseService(delegate),
-      subscription_url_(info.subscription_url),
-      list_file_(list_file),
-      load_on_start_(info.last_successful_update_attempt != base::Time::Min()),
-      initialized_(false) {}
-
-AdBlockSubscriptionService::~AdBlockSubscriptionService() {}
-
-bool AdBlockSubscriptionService::Init() {
-  if (!AdBlockBaseService::Init())
-    return false;
-
-  // if we already have local data, go ahead and load it
-  if (load_on_start_) {
-    load_on_start_ = false;
-    ReloadList();
-    // return false so we don't set the component to initialized until the data
-    // is loaded
-    return false;
-  }
-
-  return initialized_;
-}
-
-void AdBlockSubscriptionService::ReloadList() {
-  GetDATFileData(list_file_, false,
-                 base::BindOnce(&AdBlockSubscriptionService::OnListLoaded,
-                                weak_factory_.GetWeakPtr()));
-}
-
-void AdBlockSubscriptionService::OnListLoaded() {
-  Start();
-  initialized_ = true;
-}
-
-}  // namespace brave_shields
diff --git a/components/brave_shields/browser/ad_block_subscription_service.h b/components/brave_shields/browser/ad_block_subscription_service.h
deleted file mode 100644
index 16072c697398..000000000000
--- a/components/brave_shields/browser/ad_block_subscription_service.h
+++ /dev/null
@@ -1,81 +0,0 @@
-/* Copyright (c) 2021 The Brave Authors. All rights reserved.
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_SUBSCRIPTION_SERVICE_H_
-#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_SUBSCRIPTION_SERVICE_H_
-
-#include <memory>
-#include <string>
-#include <vector>
-
-#include "base/files/file_path.h"
-#include "base/time/time.h"
-#include "brave/components/brave_shields/browser/ad_block_base_service.h"
-#include "url/gurl.h"
-
-namespace base {
-template <typename StructType>
-class JSONValueConverter;
-}
-
-class AdBlockServiceTest;
-
-namespace brave_shields {
-
-struct SubscriptionInfo {
-  // The URL used to fetch the list, which is also used as a unique identifier
-  // for a subscription service.
-  GURL subscription_url;
-
-  // These are base::Time::Min() if no download has been
-  // attempted/succeeded. If a subscription has been successfully downloaded,
-  // both of these are exactly equal.
-  base::Time last_update_attempt;
-  base::Time last_successful_update_attempt;
-
-  // Any enabled list will be queried during network requests and page loads,
-  // otherwise it will be bypassed. Disabled lists will not be automatically
-  // updated.
-  bool enabled;
-
-  static void RegisterJSONConverter(
-      base::JSONValueConverter<SubscriptionInfo>*);
-};
-
-// The brave shields service in charge of ad-block checking and init
-// for a custom filter list subscription.
-class AdBlockSubscriptionService : public AdBlockBaseService {
- public:
-  using OnLoadCallback = base::RepeatingCallback<void(const GURL&)>;
-  explicit AdBlockSubscriptionService(
-      const SubscriptionInfo& info,
-      base::FilePath list_file,
-      brave_component_updater::BraveComponent::Delegate* delegate);
-  ~AdBlockSubscriptionService() override;
-
-  void ReloadList();
-
-  bool Init() override;
-
- private:
-  friend class ::AdBlockServiceTest;
-
-  void OnListLoaded();
-
-  GURL subscription_url_;
-  base::FilePath list_file_;
-  bool load_on_start_;
-  bool initialized_;
-
-  base::WeakPtrFactory<AdBlockSubscriptionService> weak_factory_{this};
-
-  AdBlockSubscriptionService(const AdBlockSubscriptionService&) = delete;
-  AdBlockSubscriptionService& operator=(const AdBlockSubscriptionService&) =
-      delete;
-};
-
-}  // namespace brave_shields
-
-#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_AD_BLOCK_SUBSCRIPTION_SERVICE_H_
diff --git a/components/brave_shields/browser/ad_block_subscription_service_manager.cc b/components/brave_shields/browser/ad_block_subscription_service_manager.cc
index f101586d9f13..9d36732c99e6 100644
--- a/components/brave_shields/browser/ad_block_subscription_service_manager.cc
+++ b/components/brave_shields/browser/ad_block_subscription_service_manager.cc
@@ -11,6 +11,7 @@
 
 #include "base/base64url.h"
 #include "base/bind.h"
+#include "base/containers/contains.h"
 #include "base/files/file_util.h"
 #include "base/json/json_value_converter.h"
 #include "base/json/values_util.h"
@@ -20,8 +21,9 @@
 #include "base/time/time.h"
 #include "base/values.h"
 #include "brave/components/adblock_rust_ffi/src/wrapper.h"
+#include "brave/components/brave_shields/browser/ad_block_engine.h"
 #include "brave/components/brave_shields/browser/ad_block_service_helper.h"
-#include "brave/components/brave_shields/browser/ad_block_subscription_service.h"
+#include "brave/components/brave_shields/browser/ad_block_subscription_filters_provider.h"
 #include "brave/components/brave_shields/browser/ad_block_subscription_service_manager_observer.h"
 #include "brave/components/brave_shields/common/brave_shield_constants.h"
 #include "brave/components/brave_shields/common/pref_names.h"
@@ -37,6 +39,19 @@ base::TimeDelta* g_testing_subscription_retry_interval;
 
 namespace {
 
+bool SkipGURLField(base::StringPiece value, GURL* field) {
+  return true;
+}
+
+bool ParseTimeValue(const base::Value* value, base::Time* field) {
+  auto time = base::ValueToTime(value);
+  if (!time) {
+    return false;
+  }
+  *field = *time;
+  return true;
+}
+
 const base::TimeDelta kListUpdateInterval = base::Days(7);
 const base::TimeDelta kListRetryInterval = base::Hours(1);
 const base::TimeDelta kListCheckInitialDelay = base::Minutes(1);
@@ -60,12 +75,30 @@ const base::FilePath::CharType kSubscriptionsDir[] =
 
 }  // namespace
 
+void SubscriptionInfo::RegisterJSONConverter(
+    base::JSONValueConverter<SubscriptionInfo>* converter) {
+  // The `subscription_url` field is skipped, as it's not stored within the
+  // JSON value and should be populated externally.
+  converter->RegisterCustomField<GURL>(
+      "subscription_url", &SubscriptionInfo::subscription_url, &SkipGURLField);
+  converter->RegisterCustomValueField<base::Time>(
+      "last_update_attempt", &SubscriptionInfo::last_update_attempt,
+      &ParseTimeValue);
+  converter->RegisterCustomValueField<base::Time>(
+      "last_successful_update_attempt",
+      &SubscriptionInfo::last_successful_update_attempt, &ParseTimeValue);
+  converter->RegisterBoolField("enabled", &SubscriptionInfo::enabled);
+}
+
 AdBlockSubscriptionServiceManager::AdBlockSubscriptionServiceManager(
-    brave_component_updater::BraveComponent::Delegate* delegate,
+    PrefService* local_state,
+    scoped_refptr<base::SequencedTaskRunner> task_runner,
     AdBlockSubscriptionDownloadManager::DownloadManagerGetter
         download_manager_getter,
     const base::FilePath& profile_dir)
-    : delegate_(delegate),
+    : initialized_(false),
+      local_state_(local_state),
+      task_runner_(task_runner),
       subscription_path_(profile_dir.Append(kSubscriptionsDir)),
       subscriptions_(new base::DictionaryValue()),
       subscription_update_timer_(
@@ -76,6 +109,16 @@ AdBlockSubscriptionServiceManager::AdBlockSubscriptionServiceManager(
           weak_ptr_factory_.GetWeakPtr()));
 }
 
+void AdBlockSubscriptionServiceManager::Init(
+    AdBlockResourceProvider* resource_provider) {
+  resource_provider_ = resource_provider;
+  initialized_ = true;
+}
+
+bool AdBlockSubscriptionServiceManager::IsInitialized() {
+  return initialized_;
+}
+
 AdBlockSubscriptionServiceManager::~AdBlockSubscriptionServiceManager() {}
 
 base::FilePath AdBlockSubscriptionServiceManager::GetSubscriptionPath(
@@ -108,15 +151,14 @@ GURL AdBlockSubscriptionServiceManager::GetListTextFileUrl(
 
 void AdBlockSubscriptionServiceManager::OnUpdateTimer(
     component_updater::TimerUpdateScheduler::OnFinishedCallback on_finished) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 
-  PrefService* local_state = delegate_->local_state();
-  if (!local_state)
+  if (!local_state_)
     return;
 
   base::AutoLock lock(subscription_services_lock_);
   subscriptions_ = base::DictionaryValue::From(base::Value::ToUniquePtrValue(
-      local_state->GetDictionary(prefs::kAdBlockListSubscriptions)->Clone()));
+      local_state_->GetDictionary(prefs::kAdBlockListSubscriptions)->Clone()));
 
   for (base::DictionaryValue::Iterator it(*subscriptions_); !it.IsAtEnd();
        it.Advance()) {
@@ -157,23 +199,40 @@ void AdBlockSubscriptionServiceManager::StartDownload(const GURL& sub_url,
 
 void AdBlockSubscriptionServiceManager::CreateSubscription(
     const GURL& sub_url) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+
+  if (base::Contains(subscription_services_, sub_url)) {
+    return;
+  }
+
   SubscriptionInfo info;
   info.subscription_url = sub_url;
   info.last_update_attempt = base::Time();
   info.last_successful_update_attempt = base::Time();
   info.enabled = true;
 
-  auto subscription_service = std::make_unique<AdBlockSubscriptionService>(
-      info, GetSubscriptionPath(sub_url).Append(kCustomSubscriptionListText),
-      delegate_);
+  auto subscription_service =
+      std::unique_ptr<AdBlockEngine, base::OnTaskRunnerDeleter>(
+          new AdBlockEngine(), base::OnTaskRunnerDeleter(task_runner_));
   UpdateSubscriptionPrefs(sub_url, info);
 
+  auto subscription_filters_provider =
+      std::make_unique<AdBlockSubscriptionFiltersProvider>(
+          local_state_,
+          GetSubscriptionPath(sub_url).Append(kCustomSubscriptionListText));
+  auto observer = std::make_unique<AdBlockService::SourceProviderObserver>(
+      subscription_service->AsWeakPtr(), subscription_filters_provider.get(),
+      resource_provider_, task_runner_);
+
   {
     base::AutoLock lock(subscription_services_lock_);
     // this could allow more than one service for a given url
     subscription_services_.insert(
         std::make_pair(sub_url, std::move(subscription_service)));
+    subscription_filters_providers_.insert(
+        std::make_pair(sub_url, std::move(subscription_filters_provider)));
+    subscription_source_observers_.insert(
+        std::make_pair(sub_url, std::move(observer)));
   }
 
   StartDownload(sub_url, true);
@@ -181,7 +240,7 @@ void AdBlockSubscriptionServiceManager::CreateSubscription(
 
 std::vector<SubscriptionInfo>
 AdBlockSubscriptionServiceManager::GetSubscriptions() {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   auto infos = std::vector<SubscriptionInfo>();
 
   for (const auto& subscription_service : subscription_services_) {
@@ -195,7 +254,7 @@ AdBlockSubscriptionServiceManager::GetSubscriptions() {
 
 void AdBlockSubscriptionServiceManager::EnableSubscription(const GURL& sub_url,
                                                            bool enabled) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   auto info = GetInfo(sub_url);
   DCHECK(info);
 
@@ -206,12 +265,18 @@ void AdBlockSubscriptionServiceManager::EnableSubscription(const GURL& sub_url,
 
 void AdBlockSubscriptionServiceManager::DeleteSubscription(
     const GURL& sub_url) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   {
     base::AutoLock lock(subscription_services_lock_);
+    auto observer = subscription_source_observers_.find(sub_url);
+    DCHECK(observer != subscription_source_observers_.end());
+    subscription_source_observers_.erase(observer);
     auto it = subscription_services_.find(sub_url);
     DCHECK(it != subscription_services_.end());
     subscription_services_.erase(it);
+    auto it2 = subscription_filters_providers_.find(sub_url);
+    DCHECK(it2 != subscription_filters_providers_.end());
+    subscription_filters_providers_.erase(it2);
   }
   ClearSubscriptionPrefs(sub_url);
 
@@ -225,13 +290,13 @@ void AdBlockSubscriptionServiceManager::DeleteSubscription(
 
 void AdBlockSubscriptionServiceManager::RefreshSubscription(const GURL& sub_url,
                                                             bool from_ui) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   StartDownload(sub_url, true);
 }
 
 void AdBlockSubscriptionServiceManager::OnGetDownloadManager(
     AdBlockSubscriptionDownloadManager* download_manager) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   download_manager_ = download_manager->AsWeakPtr();
   // base::Unretained is ok here because AdBlockSubscriptionServiceManager will
   // outlive AdBlockSubscriptionDownloadManager
@@ -277,15 +342,14 @@ absl::optional<SubscriptionInfo> AdBlockSubscriptionServiceManager::GetInfo(
 }
 
 void AdBlockSubscriptionServiceManager::LoadSubscriptionServices() {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 
-  PrefService* local_state = delegate_->local_state();
-  if (!local_state)
+  if (!local_state_)
     return;
 
   base::AutoLock lock(subscription_services_lock_);
   subscriptions_ = base::DictionaryValue::From(base::Value::ToUniquePtrValue(
-      local_state->GetDictionary(prefs::kAdBlockListSubscriptions)->Clone()));
+      local_state_->GetDictionary(prefs::kAdBlockListSubscriptions)->Clone()));
 
   for (base::DictionaryValue::Iterator it(*subscriptions_); !it.IsAtEnd();
        it.Advance()) {
@@ -297,13 +361,25 @@ void AdBlockSubscriptionServiceManager::LoadSubscriptionServices() {
       GURL sub_url(key);
       info = BuildInfoFromDict(sub_url, list_subscription_dict);
 
-      auto subscription_service = std::make_unique<AdBlockSubscriptionService>(
-          info,
-          GetSubscriptionPath(sub_url).Append(kCustomSubscriptionListText),
-          delegate_);
+      auto subscription_service =
+          std::unique_ptr<AdBlockEngine, base::OnTaskRunnerDeleter>(
+              new AdBlockEngine(), base::OnTaskRunnerDeleter(task_runner_));
+
+      auto subscription_filters_provider =
+          std::make_unique<AdBlockSubscriptionFiltersProvider>(
+              local_state_,
+              GetSubscriptionPath(sub_url).Append(kCustomSubscriptionListText));
+      auto observer = std::make_unique<AdBlockService::SourceProviderObserver>(
+          subscription_service->AsWeakPtr(),
+          subscription_filters_provider.get(), resource_provider_,
+          task_runner_);
 
       subscription_services_.insert(
           std::make_pair(sub_url, std::move(subscription_service)));
+      subscription_filters_providers_.insert(
+          std::make_pair(sub_url, std::move(subscription_filters_provider)));
+      subscription_source_observers_.insert(
+          std::make_pair(sub_url, std::move(observer)));
     }
   }
 }
@@ -313,12 +389,11 @@ void AdBlockSubscriptionServiceManager::LoadSubscriptionServices() {
 void AdBlockSubscriptionServiceManager::UpdateSubscriptionPrefs(
     const GURL& sub_url,
     const SubscriptionInfo& info) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
-  PrefService* local_state = delegate_->local_state();
-  if (!local_state)
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  if (!local_state_)
     return;
 
-  DictionaryPrefUpdate update(local_state, prefs::kAdBlockListSubscriptions);
+  DictionaryPrefUpdate update(local_state_, prefs::kAdBlockListSubscriptions);
   base::Value* subscriptions_dict = update.Get();
   auto subscription_dict = base::Value(base::Value::Type::DICTIONARY);
   subscription_dict.SetBoolKey("enabled", info.enabled);
@@ -339,12 +414,11 @@ void AdBlockSubscriptionServiceManager::UpdateSubscriptionPrefs(
 // subscription.
 void AdBlockSubscriptionServiceManager::ClearSubscriptionPrefs(
     const GURL& sub_url) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
-  PrefService* local_state = delegate_->local_state();
-  if (!local_state)
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  if (!local_state_)
     return;
 
-  DictionaryPrefUpdate update(local_state, prefs::kAdBlockListSubscriptions);
+  DictionaryPrefUpdate update(local_state_, prefs::kAdBlockListSubscriptions);
   base::Value* subscriptions_dict = update.Get();
   subscriptions_dict->RemoveKey(sub_url.spec());
 
@@ -355,10 +429,6 @@ void AdBlockSubscriptionServiceManager::ClearSubscriptionPrefs(
 }
 
 bool AdBlockSubscriptionServiceManager::Start() {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
-  for (const auto& subscription_service : subscription_services_) {
-    subscription_service.second->Start();
-  }
   return true;
 }
 
@@ -387,7 +457,7 @@ void AdBlockSubscriptionServiceManager::ShouldStartRequest(
 
 void AdBlockSubscriptionServiceManager::EnableTag(const std::string& tag,
                                                   bool enabled) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   for (const auto& subscription_service : subscription_services_) {
     subscription_service.second->EnableTag(tag, enabled);
   }
@@ -395,7 +465,7 @@ void AdBlockSubscriptionServiceManager::EnableTag(const std::string& tag,
 
 void AdBlockSubscriptionServiceManager::AddResources(
     const std::string& resources) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   for (const auto& subscription_service : subscription_services_) {
     subscription_service.second->AddResources(resources);
   }
@@ -453,9 +523,10 @@ base::Value AdBlockSubscriptionServiceManager::HiddenClassIdSelectors(
 
 void AdBlockSubscriptionServiceManager::OnSubscriptionDownloaded(
     const GURL& sub_url) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
-  auto it = subscription_services_.find(sub_url);
-  if (it == subscription_services_.end())
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  auto subscription_filters_provider =
+      subscription_filters_providers_.find(sub_url);
+  if (subscription_filters_provider == subscription_filters_providers_.end())
     return;
 
   auto info = GetInfo(sub_url);
@@ -466,7 +537,12 @@ void AdBlockSubscriptionServiceManager::OnSubscriptionDownloaded(
   info->last_successful_update_attempt = info->last_update_attempt;
   UpdateSubscriptionPrefs(sub_url, *info);
 
-  it->second->ReloadList();
+  auto subscription_source_observer =
+      subscription_source_observers_.find(sub_url);
+  DCHECK(subscription_source_observer != subscription_source_observers_.end());
+
+  subscription_filters_provider->second->LoadDAT(
+      (subscription_source_observer->second).get());
 
   NotifyObserversOfServiceEvent();
 }
diff --git a/components/brave_shields/browser/ad_block_subscription_service_manager.h b/components/brave_shields/browser/ad_block_subscription_service_manager.h
index 9931bb6e1396..f6e60df3e26c 100644
--- a/components/brave_shields/browser/ad_block_subscription_service_manager.h
+++ b/components/brave_shields/browser/ad_block_subscription_service_manager.h
@@ -15,21 +15,31 @@
 #include "base/memory/raw_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/one_shot_event.h"
+#include "base/sequence_checker.h"
 #include "base/synchronization/lock.h"
-#include "base/threading/thread_checker.h"
+#include "base/time/time.h"
 #include "base/values.h"
 #include "brave/components/brave_component_updater/browser/brave_component.h"
+#include "brave/components/brave_shields/browser/ad_block_engine.h"
+#include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/ad_block_subscription_download_manager.h"
-#include "brave/components/brave_shields/browser/ad_block_subscription_service.h"
 #include "components/component_updater/timer_update_scheduler.h"
+#include "components/prefs/pref_service.h"
 #include "third_party/abseil-cpp/absl/types/optional.h"
 #include "url/gurl.h"
 
 class PrefService;
 
+namespace base {
+template <typename StructType>
+class JSONValueConverter;
+}
+
 namespace brave_shields {
+class AdBlockResourceProvider;
 class AdBlockSubscriptionServiceManagerObserver;
-}
+class AdBlockSubscriptionFiltersProvider;
+}  // namespace brave_shields
 
 class AdBlockServiceTest;
 
@@ -37,12 +47,33 @@ using brave_component_updater::BraveComponent;
 
 namespace brave_shields {
 
+struct SubscriptionInfo {
+  // The URL used to fetch the list, which is also used as a unique identifier
+  // for a subscription service.
+  GURL subscription_url;
+
+  // These are base::Time::Min() if no download has been
+  // attempted/succeeded. If a subscription has been successfully downloaded,
+  // both of these are exactly equal.
+  base::Time last_update_attempt;
+  base::Time last_successful_update_attempt;
+
+  // Any enabled list will be queried during network requests and page loads,
+  // otherwise it will be bypassed. Disabled lists will not be automatically
+  // updated.
+  bool enabled;
+
+  static void RegisterJSONConverter(
+      base::JSONValueConverter<SubscriptionInfo>*);
+};
+
 // The AdBlock subscription service manager, in charge of initializing and
 // managing AdBlock clients corresponding to custom filter list subscriptions.
 class AdBlockSubscriptionServiceManager {
  public:
   explicit AdBlockSubscriptionServiceManager(
-      BraveComponent::Delegate* delegate,
+      PrefService* local_state,
+      scoped_refptr<base::SequencedTaskRunner> task_runner,
       AdBlockSubscriptionDownloadManager::DownloadManagerGetter getter,
       const base::FilePath& profile_dir);
   ~AdBlockSubscriptionServiceManager();
@@ -85,6 +116,9 @@ class AdBlockSubscriptionServiceManager {
   void AddObserver(AdBlockSubscriptionServiceManagerObserver* observer);
   void RemoveObserver(AdBlockSubscriptionServiceManagerObserver* observer);
 
+  void Init(AdBlockResourceProvider* resource_provider);
+  bool IsInitialized();
+
  private:
   friend class ::AdBlockServiceTest;
   // Returns the directory used to store cached list data for the given
@@ -96,7 +130,7 @@ class AdBlockSubscriptionServiceManager {
 
   void StartDownload(const GURL& sub_url, bool from_ui);
 
-  bool Init();
+  bool initialized_;
   void LoadSubscriptionServices();
   void UpdateSubscriptionPrefs(const GURL& sub_url,
                                const SubscriptionInfo& info);
@@ -110,21 +144,28 @@ class AdBlockSubscriptionServiceManager {
   void SetUpdateIntervalsForTesting(base::TimeDelta* initial_delay,
                                     base::TimeDelta* retry_interval);
 
-  raw_ptr<brave_component_updater::BraveComponent::Delegate> delegate_ =
-      nullptr;  // NOT OWNED
+  raw_ptr<PrefService> local_state_;
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+  raw_ptr<AdBlockResourceProvider> resource_provider_;
+  raw_ptr<brave_component_updater::BraveComponent::Delegate>
+      delegate_;  // NOT OWNED
   base::WeakPtr<AdBlockSubscriptionDownloadManager> download_manager_;
   base::FilePath subscription_path_;
   std::unique_ptr<base::DictionaryValue> subscriptions_;
 
-  std::map<GURL, std::unique_ptr<AdBlockSubscriptionService>>
+  std::map<GURL, std::unique_ptr<AdBlockEngine, base::OnTaskRunnerDeleter>>
       subscription_services_;
+  std::map<GURL, std::unique_ptr<AdBlockSubscriptionFiltersProvider>>
+      subscription_filters_providers_;
+  std::map<GURL, std::unique_ptr<AdBlockService::SourceProviderObserver>>
+      subscription_source_observers_;
   std::unique_ptr<component_updater::TimerUpdateScheduler>
       subscription_update_timer_;
 
   base::ObserverList<AdBlockSubscriptionServiceManagerObserver> observers_;
   base::Lock subscription_services_lock_;
 
-  THREAD_CHECKER(thread_checker_);
+  SEQUENCE_CHECKER(sequence_checker_);
 
   base::WeakPtrFactory<AdBlockSubscriptionServiceManager> weak_ptr_factory_{
       this};
diff --git a/components/brave_shields/browser/base_brave_shields_service.cc b/components/brave_shields/browser/base_brave_shields_service.cc
index 57faa8a36b67..93819a7111a6 100644
--- a/components/brave_shields/browser/base_brave_shields_service.cc
+++ b/components/brave_shields/browser/base_brave_shields_service.cc
@@ -15,15 +15,11 @@
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 
-using brave_component_updater::BraveComponent;
-
 namespace brave_shields {
 
 BaseBraveShieldsService::BaseBraveShieldsService(
-    BraveComponent::Delegate* delegate)
-    : BraveComponent(delegate),
-      initialized_(false) {
-}
+    scoped_refptr<base::SequencedTaskRunner> task_runner)
+    : initialized_(false), task_runner_(task_runner) {}
 
 BaseBraveShieldsService::~BaseBraveShieldsService() {
 }
@@ -58,4 +54,9 @@ void BaseBraveShieldsService::ShouldStartRequest(
     bool* did_match_important,
     std::string* mock_data_url) {}
 
+scoped_refptr<base::SequencedTaskRunner>
+BaseBraveShieldsService::GetTaskRunner() {
+  return task_runner_;
+}
+
 }  // namespace brave_shields
diff --git a/components/brave_shields/browser/base_brave_shields_service.h b/components/brave_shields/browser/base_brave_shields_service.h
index 781d5e3e5555..0fb0cb361242 100644
--- a/components/brave_shields/browser/base_brave_shields_service.h
+++ b/components/brave_shields/browser/base_brave_shields_service.h
@@ -25,10 +25,11 @@ namespace brave_shields {
 
 // The brave shields service in charge of checking brave shields like ad-block,
 // tracking protection, etc.
-class BaseBraveShieldsService : public BraveComponent {
+class BaseBraveShieldsService {
  public:
-  explicit BaseBraveShieldsService(BraveComponent::Delegate* delegate);
-  ~BaseBraveShieldsService() override;
+  explicit BaseBraveShieldsService(
+      scoped_refptr<base::SequencedTaskRunner> task_runner);
+  virtual ~BaseBraveShieldsService();
   bool Start();
   bool IsInitialized() const;
   virtual void ShouldStartRequest(const GURL& url,
@@ -40,6 +41,8 @@ class BaseBraveShieldsService : public BraveComponent {
                                   bool* did_match_important,
                                   std::string* mock_data_url);
 
+  scoped_refptr<base::SequencedTaskRunner> GetTaskRunner();
+
  protected:
   virtual bool Init() = 0;
 
diff --git a/components/brave_shields/browser/domain_block_controller_client.cc b/components/brave_shields/browser/domain_block_controller_client.cc
index d0c57461e2ac..3f7ce33da83f 100644
--- a/components/brave_shields/browser/domain_block_controller_client.cc
+++ b/components/brave_shields/browser/domain_block_controller_client.cc
@@ -5,7 +5,7 @@
 
 #include "brave/components/brave_shields/browser/domain_block_controller_client.h"
 
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
+#include "brave/components/brave_shields/browser/ad_block_custom_filters_provider.h"
 #include "brave/components/brave_shields/browser/domain_block_tab_storage.h"
 #include "components/prefs/pref_service.h"
 #include "components/security_interstitials/content/settings_page_helper.h"
@@ -31,7 +31,7 @@ DomainBlockControllerClient::GetMetricsHelper(const GURL& url) {
 DomainBlockControllerClient::DomainBlockControllerClient(
     content::WebContents* web_contents,
     const GURL& request_url,
-    AdBlockCustomFiltersService* ad_block_custom_filters_service,
+    AdBlockCustomFiltersProvider* ad_block_custom_filters_provider,
     ephemeral_storage::EphemeralStorageService* ephemeral_storage_service,
     PrefService* prefs,
     const std::string& locale)
@@ -43,7 +43,7 @@ DomainBlockControllerClient::DomainBlockControllerClient(
           GURL("about:blank") /* default_safe_page */,
           nullptr /* settings_page_helper */),
       request_url_(request_url),
-      ad_block_custom_filters_service_(ad_block_custom_filters_service),
+      ad_block_custom_filters_provider_(ad_block_custom_filters_provider),
       ephemeral_storage_service_(ephemeral_storage_service),
       dont_warn_again_(false) {}
 
@@ -59,8 +59,8 @@ void DomainBlockControllerClient::Proceed() {
   tab_storage->SetIsProceeding(true);
   if (dont_warn_again_) {
     std::string custom_filters =
-        ad_block_custom_filters_service_->GetCustomFilters();
-    ad_block_custom_filters_service_->UpdateCustomFilters(
+        ad_block_custom_filters_provider_->GetCustomFilters();
+    ad_block_custom_filters_provider_->UpdateCustomFilters(
         "@@||" + request_url_.host() + "^\n" + custom_filters);
   }
 
diff --git a/components/brave_shields/browser/domain_block_controller_client.h b/components/brave_shields/browser/domain_block_controller_client.h
index 0c5e86bbb972..c27ac9db4cf4 100644
--- a/components/brave_shields/browser/domain_block_controller_client.h
+++ b/components/brave_shields/browser/domain_block_controller_client.h
@@ -28,7 +28,7 @@ class EphemeralStorageService;
 
 namespace brave_shields {
 
-class AdBlockCustomFiltersService;
+class AdBlockCustomFiltersProvider;
 
 class DomainBlockControllerClient
     : public security_interstitials::SecurityInterstitialControllerClient {
@@ -39,7 +39,7 @@ class DomainBlockControllerClient
   DomainBlockControllerClient(
       content::WebContents* web_contents,
       const GURL& request_url,
-      AdBlockCustomFiltersService* ad_block_custom_filters_service,
+      AdBlockCustomFiltersProvider* ad_block_custom_filters_provider,
       ephemeral_storage::EphemeralStorageService* ephemeral_storage_service,
       PrefService* prefs,
       const std::string& locale);
@@ -60,7 +60,7 @@ class DomainBlockControllerClient
   void OnCanEnable1PESForUrl(bool can_enable_1pes);
 
   const GURL request_url_;
-  raw_ptr<AdBlockCustomFiltersService> ad_block_custom_filters_service_ =
+  raw_ptr<AdBlockCustomFiltersProvider> ad_block_custom_filters_provider_ =
       nullptr;
   raw_ptr<ephemeral_storage::EphemeralStorageService>
       ephemeral_storage_service_ = nullptr;
diff --git a/components/brave_shields/browser/domain_block_navigation_throttle.cc b/components/brave_shields/browser/domain_block_navigation_throttle.cc
index 918da3732e99..124d3e05fa7d 100644
--- a/components/brave_shields/browser/domain_block_navigation_throttle.cc
+++ b/components/brave_shields/browser/domain_block_navigation_throttle.cc
@@ -13,7 +13,6 @@
 #include "base/metrics/histogram_macros.h"
 #include "base/task/post_task.h"
 #include "base/threading/thread_task_runner_handle.h"
-#include "brave/components/brave_shields/browser/ad_block_custom_filters_service.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/domain_block_controller_client.h"
 #include "brave/components/brave_shields/browser/domain_block_page.h"
@@ -60,11 +59,11 @@ std::unique_ptr<DomainBlockNavigationThrottle>
 DomainBlockNavigationThrottle::MaybeCreateThrottleFor(
     content::NavigationHandle* navigation_handle,
     AdBlockService* ad_block_service,
-    AdBlockCustomFiltersService* ad_block_custom_filters_service,
+    AdBlockCustomFiltersProvider* ad_block_custom_filters_provider,
     ephemeral_storage::EphemeralStorageService* ephemeral_storage_service,
     HostContentSettingsMap* content_settings,
     const std::string& locale) {
-  if (!ad_block_service || !ad_block_custom_filters_service)
+  if (!ad_block_service || !ad_block_custom_filters_provider)
     return nullptr;
   if (!base::FeatureList::IsEnabled(brave_shields::features::kBraveDomainBlock))
     return nullptr;
@@ -72,20 +71,20 @@ DomainBlockNavigationThrottle::MaybeCreateThrottleFor(
   if (!navigation_handle->IsInMainFrame())
     return nullptr;
   return std::make_unique<DomainBlockNavigationThrottle>(
-      navigation_handle, ad_block_service, ad_block_custom_filters_service,
+      navigation_handle, ad_block_service, ad_block_custom_filters_provider,
       ephemeral_storage_service, content_settings, locale);
 }
 
 DomainBlockNavigationThrottle::DomainBlockNavigationThrottle(
     content::NavigationHandle* navigation_handle,
     AdBlockService* ad_block_service,
-    AdBlockCustomFiltersService* ad_block_custom_filters_service,
+    AdBlockCustomFiltersProvider* ad_block_custom_filters_provider,
     ephemeral_storage::EphemeralStorageService* ephemeral_storage_service,
     HostContentSettingsMap* content_settings,
     const std::string& locale)
     : content::NavigationThrottle(navigation_handle),
       ad_block_service_(ad_block_service),
-      ad_block_custom_filters_service_(ad_block_custom_filters_service),
+      ad_block_custom_filters_provider_(ad_block_custom_filters_provider),
       ephemeral_storage_service_(ephemeral_storage_service),
       content_settings_(content_settings),
       locale_(locale) {
@@ -100,9 +99,6 @@ content::NavigationThrottle::ThrottleCheckResult
 DomainBlockNavigationThrottle::WillStartRequest() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
-  if (!ad_block_service_->IsInitialized())
-    return content::NavigationThrottle::PROCEED;
-
   content::NavigationHandle* handle = navigation_handle();
   DCHECK(handle->IsInMainFrame());
   GURL request_url = handle->GetURL();
@@ -195,7 +191,7 @@ void DomainBlockNavigationThrottle::ShowInterstitial() {
   // The controller client implements the actual logic to "go back" or "proceed"
   // from the interstitial.
   auto controller_client = std::make_unique<DomainBlockControllerClient>(
-      web_contents, request_url, ad_block_custom_filters_service_,
+      web_contents, request_url, ad_block_custom_filters_provider_,
       ephemeral_storage_service_, pref_service, locale_);
 
   // This handles populating the HTML template of the interstitial page with
diff --git a/components/brave_shields/browser/domain_block_navigation_throttle.h b/components/brave_shields/browser/domain_block_navigation_throttle.h
index a8b228d24c66..90ac0015e1c6 100644
--- a/components/brave_shields/browser/domain_block_navigation_throttle.h
+++ b/components/brave_shields/browser/domain_block_navigation_throttle.h
@@ -29,14 +29,14 @@ class EphemeralStorageService;
 namespace brave_shields {
 
 class AdBlockService;
-class AdBlockCustomFiltersService;
+class AdBlockCustomFiltersProvider;
 
 class DomainBlockNavigationThrottle : public content::NavigationThrottle {
  public:
   explicit DomainBlockNavigationThrottle(
       content::NavigationHandle* navigation_handle,
       AdBlockService* ad_block_service,
-      AdBlockCustomFiltersService* ad_block_custom_filters_service,
+      AdBlockCustomFiltersProvider* ad_block_custom_filters_provider,
       ephemeral_storage::EphemeralStorageService* ephemeral_storage_service,
       HostContentSettingsMap* content_settings,
       const std::string& locale);
@@ -49,7 +49,7 @@ class DomainBlockNavigationThrottle : public content::NavigationThrottle {
   static std::unique_ptr<DomainBlockNavigationThrottle> MaybeCreateThrottleFor(
       content::NavigationHandle* navigation_handle,
       AdBlockService* ad_block_service,
-      AdBlockCustomFiltersService* ad_block_custom_filters_service,
+      AdBlockCustomFiltersProvider* ad_block_custom_filters_provider,
       ephemeral_storage::EphemeralStorageService* ephemeral_storage_service,
       HostContentSettingsMap* content_settings,
       const std::string& locale);
@@ -68,7 +68,7 @@ class DomainBlockNavigationThrottle : public content::NavigationThrottle {
   void Enable1PESAndResume();
 
   AdBlockService* ad_block_service_ = nullptr;
-  AdBlockCustomFiltersService* ad_block_custom_filters_service_ = nullptr;
+  AdBlockCustomFiltersProvider* ad_block_custom_filters_provider_ = nullptr;
   ephemeral_storage::EphemeralStorageService* ephemeral_storage_service_ =
       nullptr;
   HostContentSettingsMap* content_settings_ = nullptr;
diff --git a/components/brave_shields/browser/https_everywhere_component_installer.cc b/components/brave_shields/browser/https_everywhere_component_installer.cc
new file mode 100644
index 000000000000..108d61bba0fb
--- /dev/null
+++ b/components/brave_shields/browser/https_everywhere_component_installer.cc
@@ -0,0 +1,167 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "brave/components/brave_shields/browser/https_everywhere_component_installer.h"
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "base/base64.h"
+#include "base/bind.h"
+#include "base/callback.h"
+#include "brave/components/brave_component_updater/browser/brave_on_demand_updater.h"
+#include "components/component_updater/component_installer.h"
+#include "components/component_updater/component_updater_service.h"
+#include "crypto/sha2.h"
+
+using brave_component_updater::BraveOnDemandUpdater;
+
+namespace brave_shields {
+
+namespace {
+
+constexpr size_t kHashSize = 32;
+const char kHTTPSEverywhereComponentName[] = "Brave HTTPS Everywhere Updater";
+const char kHTTPSEverywhereComponentId[] = "oofiananboodjbbmdelgdommihjbkfag";
+const char kHTTPSEverywhereComponentBase64PublicKey[] =
+    "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvn9zSMjTmhkQyrZu5UdN"
+    "350nPqLoSeCYngcC7yDFwaUHjoBQXCZqGeDC69ciCQ2mlRhcV2nxXqlUDkiC6+7m"
+    "651nI+gi4oVqHagc7EFUyGA0yuIk7qIMvCBdH7wbET27de0rzbRzRht9EKzEjIhC"
+    "BtoPnmyrO/8qPrH4XR4cPfnFPuJssBBxC1B35H7rh0Br9qePhPDDe9OjyqYxPuio"
+    "+YcC9obL4g5krVrfrlKLfFNpIewUcJyBpSlCgfxEyEhgDkK9cILTMUi5vC7GxS3P"
+    "OtZqgfRg8Da4i+NwmjQqrz0JFtPMMSyUnmeMj+mSOL4xZVWr8fU2/GOCXs9gczDp"
+    "JwIDAQAB";
+
+class HTTPSEverywhereComponentInstallerPolicy
+    : public component_updater::ComponentInstallerPolicy {
+ public:
+  explicit HTTPSEverywhereComponentInstallerPolicy(
+      const std::string& component_public_key,
+      const std::string& component_id,
+      const std::string& component_name,
+      OnComponentReadyCallback callback);
+  ~HTTPSEverywhereComponentInstallerPolicy() override;
+
+  HTTPSEverywhereComponentInstallerPolicy(
+      const HTTPSEverywhereComponentInstallerPolicy&) = delete;
+  HTTPSEverywhereComponentInstallerPolicy& operator=(
+      const HTTPSEverywhereComponentInstallerPolicy&) = delete;
+
+  // component_updater::ComponentInstallerPolicy
+  bool SupportsGroupPolicyEnabledComponentUpdates() const override;
+  bool RequiresNetworkEncryption() const override;
+  update_client::CrxInstaller::Result OnCustomInstall(
+      const base::DictionaryValue& manifest,
+      const base::FilePath& install_dir) override;
+  void OnCustomUninstall() override;
+  bool VerifyInstallation(const base::DictionaryValue& manifest,
+                          const base::FilePath& install_dir) const override;
+  void ComponentReady(const base::Version& version,
+                      const base::FilePath& path,
+                      std::unique_ptr<base::DictionaryValue> manifest) override;
+  base::FilePath GetRelativeInstallDir() const override;
+  void GetHash(std::vector<uint8_t>* hash) const override;
+  std::string GetName() const override;
+  update_client::InstallerAttributes GetInstallerAttributes() const override;
+
+ private:
+  const std::string component_id_;
+  const std::string component_name_;
+  OnComponentReadyCallback ready_callback_;
+  uint8_t component_hash_[kHashSize];
+};
+
+HTTPSEverywhereComponentInstallerPolicy::
+    HTTPSEverywhereComponentInstallerPolicy(
+        const std::string& component_public_key,
+        const std::string& component_id,
+        const std::string& component_name,
+        OnComponentReadyCallback callback)
+    : component_id_(component_id),
+      component_name_(component_name),
+      ready_callback_(callback) {
+  // Generate hash from public key.
+  std::string decoded_public_key;
+  base::Base64Decode(component_public_key, &decoded_public_key);
+  crypto::SHA256HashString(decoded_public_key, component_hash_, kHashSize);
+}
+
+HTTPSEverywhereComponentInstallerPolicy::
+    ~HTTPSEverywhereComponentInstallerPolicy() = default;
+
+bool HTTPSEverywhereComponentInstallerPolicy::
+    SupportsGroupPolicyEnabledComponentUpdates() const {
+  return true;
+}
+
+bool HTTPSEverywhereComponentInstallerPolicy::RequiresNetworkEncryption()
+    const {
+  return false;
+}
+
+update_client::CrxInstaller::Result
+HTTPSEverywhereComponentInstallerPolicy::OnCustomInstall(
+    const base::DictionaryValue& manifest,
+    const base::FilePath& install_dir) {
+  return update_client::CrxInstaller::Result(0);
+}
+
+void HTTPSEverywhereComponentInstallerPolicy::OnCustomUninstall() {}
+
+void HTTPSEverywhereComponentInstallerPolicy::ComponentReady(
+    const base::Version& version,
+    const base::FilePath& path,
+    std::unique_ptr<base::DictionaryValue> manifest) {
+  ready_callback_.Run(path);
+}
+
+bool HTTPSEverywhereComponentInstallerPolicy::VerifyInstallation(
+    const base::DictionaryValue& manifest,
+    const base::FilePath& install_dir) const {
+  return true;
+}
+
+base::FilePath HTTPSEverywhereComponentInstallerPolicy::GetRelativeInstallDir()
+    const {
+  return base::FilePath::FromUTF8Unsafe(component_id_);
+}
+
+void HTTPSEverywhereComponentInstallerPolicy::GetHash(
+    std::vector<uint8_t>* hash) const {
+  hash->assign(component_hash_, component_hash_ + kHashSize);
+}
+
+std::string HTTPSEverywhereComponentInstallerPolicy::GetName() const {
+  return component_name_;
+}
+
+update_client::InstallerAttributes
+HTTPSEverywhereComponentInstallerPolicy::GetInstallerAttributes() const {
+  return update_client::InstallerAttributes();
+}
+
+void OnRegistered(const std::string& component_id) {
+  BraveOnDemandUpdater::GetInstance()->OnDemandUpdate(component_id);
+}
+
+}  // namespace
+
+void RegisterHTTPSEverywhereComponent(
+    component_updater::ComponentUpdateService* cus,
+    OnComponentReadyCallback callback) {
+  // In test, |cus| could be nullptr.
+  if (!cus)
+    return;
+
+  auto installer = base::MakeRefCounted<component_updater::ComponentInstaller>(
+      std::make_unique<HTTPSEverywhereComponentInstallerPolicy>(
+          kHTTPSEverywhereComponentBase64PublicKey, kHTTPSEverywhereComponentId,
+          kHTTPSEverywhereComponentName, callback));
+  installer->Register(
+      cus, base::BindOnce(&OnRegistered, kHTTPSEverywhereComponentId));
+}
+
+}  // namespace brave_shields
diff --git a/components/brave_shields/browser/https_everywhere_component_installer.h b/components/brave_shields/browser/https_everywhere_component_installer.h
new file mode 100644
index 000000000000..bcee4ec6875b
--- /dev/null
+++ b/components/brave_shields/browser/https_everywhere_component_installer.h
@@ -0,0 +1,29 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_HTTPS_EVERYWHERE_COMPONENT_INSTALLER_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_HTTPS_EVERYWHERE_COMPONENT_INSTALLER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
+
+namespace component_updater {
+class ComponentUpdateService;
+}  // namespace component_updater
+
+namespace brave_shields {
+
+using OnComponentReadyCallback =
+    base::RepeatingCallback<void(const base::FilePath& install_path)>;
+
+void RegisterHTTPSEverywhereComponent(
+    component_updater::ComponentUpdateService* cus,
+    OnComponentReadyCallback callback);
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_HTTPS_EVERYWHERE_COMPONENT_INSTALLER_H_
diff --git a/components/brave_shields/browser/https_everywhere_service.cc b/components/brave_shields/browser/https_everywhere_service.cc
index b8d866e827dc..28822f42ce72 100644
--- a/components/brave_shields/browser/https_everywhere_service.cc
+++ b/components/brave_shields/browser/https_everywhere_service.cc
@@ -79,46 +79,15 @@ std::string leveldbGet(leveldb::DB* db, const std::string &key) {
 
 namespace brave_shields {
 
-const char kHTTPSEverywhereComponentName[] = "Brave HTTPS Everywhere Updater";
-const char kHTTPSEverywhereComponentId[] = "oofiananboodjbbmdelgdommihjbkfag";
-const char kHTTPSEverywhereComponentBase64PublicKey[] =
-    "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvn9zSMjTmhkQyrZu5UdN"
-    "350nPqLoSeCYngcC7yDFwaUHjoBQXCZqGeDC69ciCQ2mlRhcV2nxXqlUDkiC6+7m"
-    "651nI+gi4oVqHagc7EFUyGA0yuIk7qIMvCBdH7wbET27de0rzbRzRht9EKzEjIhC"
-    "BtoPnmyrO/8qPrH4XR4cPfnFPuJssBBxC1B35H7rh0Br9qePhPDDe9OjyqYxPuio"
-    "+YcC9obL4g5krVrfrlKLfFNpIewUcJyBpSlCgfxEyEhgDkK9cILTMUi5vC7GxS3P"
-    "OtZqgfRg8Da4i+NwmjQqrz0JFtPMMSyUnmeMj+mSOL4xZVWr8fU2/GOCXs9gczDp"
-    "JwIDAQAB";
-
-bool HTTPSEverywhereService::g_ignore_port_for_test_(false);
-std::string HTTPSEverywhereService::g_https_everywhere_component_id_(
-    kHTTPSEverywhereComponentId);
-std::string
-HTTPSEverywhereService::g_https_everywhere_component_base64_public_key_(
-    kHTTPSEverywhereComponentBase64PublicKey);
-
-HTTPSEverywhereService::HTTPSEverywhereService(
-    BraveComponent::Delegate* delegate)
-    : BaseBraveShieldsService(delegate),
-      level_db_(nullptr) {
+HTTPSEverywhereService::Engine::Engine(HTTPSEverywhereService* service)
+    : level_db_(nullptr), service_(service) {
   DETACH_FROM_SEQUENCE(sequence_checker_);
 }
 
-HTTPSEverywhereService::~HTTPSEverywhereService() {
-  GetTaskRunner()->DeleteSoon(FROM_HERE, level_db_);
-}
-
-bool HTTPSEverywhereService::Init() {
-  Register(kHTTPSEverywhereComponentName,
-           g_https_everywhere_component_id_,
-           g_https_everywhere_component_base64_public_key_);
-  return true;
-}
-
-void HTTPSEverywhereService::InitDB(const base::FilePath& install_dir) {
+void HTTPSEverywhereService::Engine::Init(const base::FilePath& base_dir) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   base::FilePath zip_db_file_path =
-      install_dir.AppendASCII(DAT_FILE_VERSION).AppendASCII(DAT_FILE);
+      base_dir.AppendASCII(DAT_FILE_VERSION).AppendASCII(DAT_FILE);
   base::FilePath unzipped_level_db_path = zip_db_file_path.RemoveExtension();
   base::FilePath destination = zip_db_file_path.DirName();
   if (!zip::Unzip(zip_db_file_path, destination)) {
@@ -143,16 +112,7 @@ void HTTPSEverywhereService::InitDB(const base::FilePath& install_dir) {
   }
 }
 
-void HTTPSEverywhereService::OnComponentReady(
-    const std::string& component_id,
-    const base::FilePath& install_dir,
-    const std::string& manifest) {
-  GetTaskRunner()->PostTask(
-      FROM_HERE, base::BindOnce(&HTTPSEverywhereService::InitDB, AsWeakPtr(),
-                                install_dir));
-}
-
-bool HTTPSEverywhereService::GetHTTPSURL(
+bool HTTPSEverywhereService::Engine::GetHTTPSURL(
     const GURL* url,
     const uint64_t& request_identifier,
     std::string* new_url) {
@@ -161,15 +121,16 @@ bool HTTPSEverywhereService::GetHTTPSURL(
   if (!url->is_valid())
     return false;
 
-  if (!IsInitialized() || !level_db_ || url->scheme() == url::kHttpsScheme) {
+  if (!level_db_ || url->scheme() == url::kHttpsScheme) {
     return false;
   }
-  if (!ShouldHTTPSERedirect(request_identifier)) {
+
+  if (!service_->ShouldHTTPSERedirect(request_identifier)) {
     return false;
   }
 
-  if (recently_used_cache_.get(url->spec(), new_url)) {
-    AddHTTPSEUrlToRedirectList(request_identifier);
+  if (service_->recently_used_cache().get(url->spec(), new_url)) {
+    service_->AddHTTPSEUrlToRedirectList(request_identifier);
     return true;
   }
 
@@ -188,80 +149,17 @@ bool HTTPSEverywhereService::GetHTTPSURL(
     if (!value.empty()) {
       *new_url = ApplyHTTPSRule(candidate_url.spec(), value);
       if (0 != new_url->length()) {
-        recently_used_cache_.add(candidate_url.spec(), *new_url);
-        AddHTTPSEUrlToRedirectList(request_identifier);
+        service_->recently_used_cache().add(candidate_url.spec(), *new_url);
+        service_->AddHTTPSEUrlToRedirectList(request_identifier);
         return true;
       }
     }
   }
-  recently_used_cache_.remove(candidate_url.spec());
-  return false;
-}
-
-bool HTTPSEverywhereService::GetHTTPSURLFromCacheOnly(
-    const GURL* url,
-    const uint64_t& request_identifier,
-    std::string* cached_url) {
-  if (!url->is_valid())
-    return false;
-
-  if (!IsInitialized() || url->scheme() == url::kHttpsScheme) {
-    return false;
-  }
-  if (!ShouldHTTPSERedirect(request_identifier)) {
-    return false;
-  }
-
-  if (recently_used_cache_.get(url->spec(), cached_url)) {
-    AddHTTPSEUrlToRedirectList(request_identifier);
-    return true;
-  }
+  service_->recently_used_cache().remove(candidate_url.spec());
   return false;
 }
 
-bool HTTPSEverywhereService::ShouldHTTPSERedirect(
-    const uint64_t& request_identifier) {
-  base::AutoLock auto_lock(httpse_get_urls_redirects_count_mutex_);
-  for (size_t i = 0; i < httpse_urls_redirects_count_.size(); i++) {
-    if (request_identifier ==
-        httpse_urls_redirects_count_[i].request_identifier_ &&
-        httpse_urls_redirects_count_[i].redirects_ >=
-        HTTPSE_URL_MAX_REDIRECTS_COUNT - 1) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
-void HTTPSEverywhereService::AddHTTPSEUrlToRedirectList(
-    const uint64_t& request_identifier) {
-  // Adding redirects count for the current request
-  base::AutoLock auto_lock(httpse_get_urls_redirects_count_mutex_);
-  bool hostFound = false;
-  for (size_t i = 0; i < httpse_urls_redirects_count_.size(); i++) {
-    if (request_identifier ==
-        httpse_urls_redirects_count_[i].request_identifier_) {
-      // Found the host, just increment the redirects_count
-      httpse_urls_redirects_count_[i].redirects_++;
-      hostFound = true;
-      break;
-    }
-  }
-  if (!hostFound) {
-      // The host is new, adding it to the redirects list
-      if (httpse_urls_redirects_count_.size() >=
-          HTTPSE_URLS_REDIRECTS_COUNT_QUEUE) {
-          // The queue is full, erase the first element
-          httpse_urls_redirects_count_.erase(
-              httpse_urls_redirects_count_.begin());
-      }
-      httpse_urls_redirects_count_.push_back(
-          HTTPSE_REDIRECTS_COUNT_ST(request_identifier, 1));
-  }
-}
-
-std::string HTTPSEverywhereService::ApplyHTTPSRule(
+std::string HTTPSEverywhereService::Engine::ApplyHTTPSRule(
     const std::string& originalUrl,
     const std::string& rule) {
   absl::optional<base::Value> json_object = base::JSONReader::Read(rule);
@@ -361,7 +259,7 @@ std::string HTTPSEverywhereService::ApplyHTTPSRule(
   return "";
 }
 
-std::string HTTPSEverywhereService::CorrecttoRuleToRE2Engine(
+std::string HTTPSEverywhereService::Engine::CorrecttoRuleToRE2Engine(
     const std::string& to) {
   std::string correctedto(to);
   size_t pos = to.find("$");
@@ -373,7 +271,7 @@ std::string HTTPSEverywhereService::CorrecttoRuleToRE2Engine(
   return correctedto;
 }
 
-void HTTPSEverywhereService::CloseDatabase() {
+void HTTPSEverywhereService::Engine::CloseDatabase() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   if (level_db_) {
     delete level_db_;
@@ -381,12 +279,94 @@ void HTTPSEverywhereService::CloseDatabase() {
   }
 }
 
-// static
-void HTTPSEverywhereService::SetComponentIdAndBase64PublicKeyForTest(
-    const std::string& component_id,
-    const std::string& component_base64_public_key) {
-  g_https_everywhere_component_id_ = component_id;
-  g_https_everywhere_component_base64_public_key_ = component_base64_public_key;
+bool HTTPSEverywhereService::g_ignore_port_for_test_(false);
+
+HTTPSEverywhereService::HTTPSEverywhereService(
+    scoped_refptr<base::SequencedTaskRunner> task_runner)
+    : BaseBraveShieldsService(task_runner),
+      engine_(new Engine(this), base::OnTaskRunnerDeleter(task_runner)) {}
+
+HTTPSEverywhereService::~HTTPSEverywhereService() {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+}
+
+bool HTTPSEverywhereService::Init() {
+  return true;
+}
+
+void HTTPSEverywhereService::InitDB(const base::FilePath& install_dir) {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  GetTaskRunner()->PostTask(
+      FROM_HERE,
+      base::BindOnce(&Engine::Init, engine_->AsWeakPtr(), install_dir));
+}
+
+bool HTTPSEverywhereService::GetHTTPSURLFromCacheOnly(
+    const GURL* url,
+    const uint64_t& request_identifier,
+    std::string* cached_url) {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  if (!url->is_valid())
+    return false;
+
+  if (!IsInitialized() || url->scheme() == url::kHttpsScheme) {
+    return false;
+  }
+  if (!ShouldHTTPSERedirect(request_identifier)) {
+    return false;
+  }
+
+  if (recently_used_cache_.get(url->spec(), cached_url)) {
+    AddHTTPSEUrlToRedirectList(request_identifier);
+    return true;
+  }
+  return false;
+}
+
+HTTPSERecentlyUsedCache<std::string>&
+HTTPSEverywhereService::recently_used_cache() {
+  return recently_used_cache_;
+}
+
+bool HTTPSEverywhereService::ShouldHTTPSERedirect(
+    const uint64_t& request_identifier) {
+  base::AutoLock auto_lock(httpse_get_urls_redirects_count_mutex_);
+  for (size_t i = 0; i < httpse_urls_redirects_count_.size(); i++) {
+    if (request_identifier ==
+            httpse_urls_redirects_count_[i].request_identifier_ &&
+        httpse_urls_redirects_count_[i].redirects_ >=
+            HTTPSE_URL_MAX_REDIRECTS_COUNT - 1) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+void HTTPSEverywhereService::AddHTTPSEUrlToRedirectList(
+    const uint64_t& request_identifier) {
+  // Adding redirects count for the current request
+  base::AutoLock auto_lock(httpse_get_urls_redirects_count_mutex_);
+  bool hostFound = false;
+  for (size_t i = 0; i < httpse_urls_redirects_count_.size(); i++) {
+    if (request_identifier ==
+        httpse_urls_redirects_count_[i].request_identifier_) {
+      // Found the host, just increment the redirects_count
+      httpse_urls_redirects_count_[i].redirects_++;
+      hostFound = true;
+      break;
+    }
+  }
+  if (!hostFound) {
+    // The host is new, adding it to the redirects list
+    if (httpse_urls_redirects_count_.size() >=
+        HTTPSE_URLS_REDIRECTS_COUNT_QUEUE) {
+      // The queue is full, erase the first element
+      httpse_urls_redirects_count_.erase(httpse_urls_redirects_count_.begin());
+    }
+    httpse_urls_redirects_count_.push_back(
+        HTTPSE_REDIRECTS_COUNT_ST(request_identifier, 1));
+  }
 }
 
 // static
@@ -399,8 +379,8 @@ void HTTPSEverywhereService::SetIgnorePortForTest(bool ignore) {
 // The brave shields factory. Using the Brave Shields as a singleton
 // is the job of the browser process.
 std::unique_ptr<HTTPSEverywhereService> HTTPSEverywhereServiceFactory(
-    BraveComponent::Delegate* delegate) {
-  return std::make_unique<HTTPSEverywhereService>(delegate);
+    scoped_refptr<base::SequencedTaskRunner> task_runner) {
+  return std::make_unique<HTTPSEverywhereService>(task_runner);
 }
 
 }  // namespace brave_shields
diff --git a/components/brave_shields/browser/https_everywhere_service.h b/components/brave_shields/browser/https_everywhere_service.h
index a0309cd84b3d..a227d5ce6fef 100644
--- a/components/brave_shields/browser/https_everywhere_service.h
+++ b/components/brave_shields/browser/https_everywhere_service.h
@@ -43,57 +43,68 @@ struct HTTPSE_REDIRECTS_COUNT_ST {
   unsigned int redirects_;
 };
 
-class HTTPSEverywhereService : public BaseBraveShieldsService,
-                         public base::SupportsWeakPtr<HTTPSEverywhereService> {
+class HTTPSEverywhereService : public BaseBraveShieldsService {
  public:
-  explicit HTTPSEverywhereService(BraveComponent::Delegate* delegate);
+  explicit HTTPSEverywhereService(
+      scoped_refptr<base::SequencedTaskRunner> task_runner);
   HTTPSEverywhereService(const HTTPSEverywhereService&) = delete;
   HTTPSEverywhereService& operator=(const HTTPSEverywhereService&) = delete;
   ~HTTPSEverywhereService() override;
-  bool GetHTTPSURL(const GURL* url,
-                   const uint64_t& request_id,
-                   std::string* new_url);
+
+  class Engine : public base::SupportsWeakPtr<Engine> {
+   public:
+    explicit Engine(HTTPSEverywhereService* service);
+    Engine(const Engine&) = delete;
+    Engine& operator=(const Engine&) = delete;
+
+    void Init(const base::FilePath& base_dir);
+    bool GetHTTPSURL(const GURL* url,
+                     const uint64_t& request_id,
+                     std::string* new_url);
+
+   private:
+    std::string ApplyHTTPSRule(const std::string& originalUrl,
+                               const std::string& rule);
+    std::string CorrecttoRuleToRE2Engine(const std::string& to);
+    void CloseDatabase();
+
+    leveldb::DB* level_db_;
+    HTTPSEverywhereService* service_;  // not owned
+    SEQUENCE_CHECKER(sequence_checker_);
+  };
+
+  void InitDB(const base::FilePath& install_dir);
+
   bool GetHTTPSURLFromCacheOnly(const GURL* url,
                                 const uint64_t& request_id,
                                 std::string* cached_url);
 
+  base::WeakPtr<Engine> engine() { return engine_->AsWeakPtr(); }
+
  protected:
   bool Init() override;
-  void OnComponentReady(const std::string& component_id,
-      const base::FilePath& install_dir,
-      const std::string& manifest) override;
-
-  void AddHTTPSEUrlToRedirectList(const uint64_t& request_id);
-  bool ShouldHTTPSERedirect(const uint64_t& request_id);
-  std::string ApplyHTTPSRule(const std::string& originalUrl,
-      const std::string& rule);
-  std::string CorrecttoRuleToRE2Engine(const std::string& to);
 
  private:
   friend class ::HTTPSEverywhereServiceTest;
+  friend class Engine;
   static bool g_ignore_port_for_test_;
-  static std::string g_https_everywhere_component_id_;
-  static std::string g_https_everywhere_component_base64_public_key_;
   static void SetIgnorePortForTest(bool ignore);
-  static void SetComponentIdAndBase64PublicKeyForTest(
-      const std::string& component_id,
-      const std::string& component_base64_public_key);
-
-  void CloseDatabase();
 
-  void InitDB(const base::FilePath& install_dir);
+  void AddHTTPSEUrlToRedirectList(const uint64_t& request_id);
+  bool ShouldHTTPSERedirect(const uint64_t& request_id);
+  HTTPSERecentlyUsedCache<std::string>& recently_used_cache();
 
   base::Lock httpse_get_urls_redirects_count_mutex_;
   std::vector<HTTPSE_REDIRECTS_COUNT_ST> httpse_urls_redirects_count_;
   HTTPSERecentlyUsedCache<std::string> recently_used_cache_;
-  leveldb::DB* level_db_;
+  std::unique_ptr<Engine, base::OnTaskRunnerDeleter> engine_;
 
   SEQUENCE_CHECKER(sequence_checker_);
 };
 
 // Creates the HTTPSEverywhereService
 std::unique_ptr<HTTPSEverywhereService> HTTPSEverywhereServiceFactory(
-    BraveComponent::Delegate* delegate);
+    scoped_refptr<base::SequencedTaskRunner> task_runner);
 
 }  // namespace brave_shields
 
diff --git a/components/brave_shields/browser/https_everywhere_service_browsertest.cc b/components/brave_shields/browser/https_everywhere_service_browsertest.cc
index 87283f289cf3..3da1ad9ff24a 100644
--- a/components/brave_shields/browser/https_everywhere_service_browsertest.cc
+++ b/components/brave_shields/browser/https_everywhere_service_browsertest.cc
@@ -7,6 +7,7 @@
 #include "base/task/post_task.h"
 #include "base/test/thread_test_helper.h"
 #include "brave/browser/brave_browser_process.h"
+#include "brave/browser/brave_shields/https_everywhere_component_installer.h"
 #include "brave/common/brave_paths.h"
 #include "brave/components/brave_shields/browser/https_everywhere_service.h"
 #include "chrome/browser/extensions/extension_browsertest.h"
@@ -63,10 +64,9 @@ class HTTPSEverywhereServiceTest : public ExtensionBrowserTest {
 
   void InitService() {
     brave_shields::HTTPSEverywhereService::SetIgnorePortForTest(true);
-    brave_shields::HTTPSEverywhereService::
-        SetComponentIdAndBase64PublicKeyForTest(
-            kHTTPSEverywhereComponentTestId,
-            kHTTPSEverywhereComponentTestBase64PublicKey);
+    brave_shields::SetHTTPSEverywhereComponentIdAndBase64PublicKeyForTest(
+        kHTTPSEverywhereComponentTestId,
+        kHTTPSEverywhereComponentTestBase64PublicKey);
   }
 
   void GetTestDataDir(base::FilePath* test_data_dir) {
@@ -82,8 +82,8 @@ class HTTPSEverywhereServiceTest : public ExtensionBrowserTest {
     if (!httpse_extension)
       return false;
 
-    g_brave_browser_process->https_everywhere_service()->OnComponentReady(
-        httpse_extension->id(), httpse_extension->path(), "");
+    g_brave_browser_process->https_everywhere_service()->InitDB(
+        httpse_extension->path());
     WaitForHTTPSEverywhereServiceThread();
 
     return true;
diff --git a/components/brave_shields/browser/test_filters_provider.cc b/components/brave_shields/browser/test_filters_provider.cc
new file mode 100644
index 000000000000..2d191d07a24c
--- /dev/null
+++ b/components/brave_shields/browser/test_filters_provider.cc
@@ -0,0 +1,45 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "brave/components/brave_shields/browser/test_filters_provider.h"
+
+#include <string>
+#include <utility>
+
+namespace brave_shields {
+
+TestFiltersProvider::TestFiltersProvider(const std::string& rules,
+                                         const std::string& resources)
+    : rules_(rules), resources_(resources) {}
+
+TestFiltersProvider::TestFiltersProvider(const base::FilePath& dat_location,
+                                         const std::string& resources)
+    : resources_(resources) {
+  CHECK(!dat_location.empty());
+
+  dat_buffer_ = brave_component_updater::ReadDATFileData(dat_location);
+
+  CHECK(!dat_buffer_.empty());
+}
+
+TestFiltersProvider::~TestFiltersProvider() {}
+
+void TestFiltersProvider::LoadDATBuffer(
+    base::OnceCallback<void(bool deserialize, const DATFileDataBuffer& dat_buf)>
+        cb) {
+  if (dat_buffer_.empty()) {
+    auto buffer = std::vector<unsigned char>(rules_.begin(), rules_.end());
+    std::move(cb).Run(false, buffer);
+  } else {
+    std::move(cb).Run(true, dat_buffer_);
+  }
+}
+
+void TestFiltersProvider::LoadResources(
+    base::OnceCallback<void(const std::string& resources_json)> cb) {
+  std::move(cb).Run(resources_);
+}
+
+}  // namespace brave_shields
diff --git a/components/brave_shields/browser/test_filters_provider.h b/components/brave_shields/browser/test_filters_provider.h
new file mode 100644
index 000000000000..bf0c72d1d97e
--- /dev/null
+++ b/components/brave_shields/browser/test_filters_provider.h
@@ -0,0 +1,45 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_TEST_FILTERS_PROVIDER_H_
+#define BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_TEST_FILTERS_PROVIDER_H_
+
+#include <string>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
+#include "brave/components/brave_component_updater/browser/dat_file_util.h"
+#include "brave/components/brave_shields/browser/ad_block_filters_provider.h"
+#include "brave/components/brave_shields/browser/ad_block_resource_provider.h"
+
+using brave_component_updater::DATFileDataBuffer;
+
+namespace brave_shields {
+
+class TestFiltersProvider : public AdBlockFiltersProvider,
+                            public AdBlockResourceProvider {
+ public:
+  TestFiltersProvider(const std::string& rules, const std::string& resources);
+  TestFiltersProvider(const base::FilePath& dat_location,
+                      const std::string& resources);
+  ~TestFiltersProvider() override;
+
+  void LoadDATBuffer(
+      base::OnceCallback<void(bool deserialize,
+                              const DATFileDataBuffer& dat_buf)> cb) override;
+
+  void LoadResources(
+      base::OnceCallback<void(const std::string& resources_json)> cb) override;
+
+ private:
+  DATFileDataBuffer dat_buffer_;
+  std::string rules_;
+  std::string resources_;
+};
+
+}  // namespace brave_shields
+
+#endif  // BRAVE_COMPONENTS_BRAVE_SHIELDS_BROWSER_TEST_FILTERS_PROVIDER_H_
diff --git a/components/cosmetic_filters/browser/cosmetic_filters_resources.cc b/components/cosmetic_filters/browser/cosmetic_filters_resources.cc
index bfcdb57e154b..206fdced84a7 100644
--- a/components/cosmetic_filters/browser/cosmetic_filters_resources.cc
+++ b/components/cosmetic_filters/browser/cosmetic_filters_resources.cc
@@ -26,6 +26,7 @@ void CosmeticFiltersResources::HiddenClassIdSelectors(
     const std::string& input,
     const std::vector<std::string>& exceptions,
     HiddenClassIdSelectorsCallback callback) {
+  DCHECK(ad_block_service_->GetTaskRunner()->RunsTasksInCurrentSequence());
   absl::optional<base::Value> input_value = base::JSONReader::Read(input);
   if (!input_value || !input_value->is_dict()) {
     // Nothing to work with
@@ -69,6 +70,7 @@ void CosmeticFiltersResources::HiddenClassIdSelectors(
 void CosmeticFiltersResources::UrlCosmeticResources(
     const std::string& url,
     UrlCosmeticResourcesCallback callback) {
+  DCHECK(ad_block_service_->GetTaskRunner()->RunsTasksInCurrentSequence());
   auto resources = ad_block_service_->UrlCosmeticResources(url);
   std::move(callback).Run(resources ? std::move(resources.value())
                                     : base::Value());
diff --git a/test/BUILD.gn b/test/BUILD.gn
index 040019cd6a1d..29b951d6c8df 100644
--- a/test/BUILD.gn
+++ b/test/BUILD.gn
@@ -121,6 +121,7 @@ test("brave_unit_tests") {
     "//brave/components/brave_shields/browser/cosmetic_merge_unittest.cc",
     "//brave/components/brave_shields/browser/csp_merge_unittest.cc",
     "//brave/components/brave_shields/browser/https_everywhere_recently_used_cache_unittest.cpp",
+    "//brave/components/brave_shields/browser/test_filters_provider.cc",
     "//brave/components/brave_sync/crypto/crypto_unittest.cc",
     "//brave/components/content_settings/core/browser/brave_content_settings_pref_provider_unittest.cc",
     "//brave/components/content_settings/core/browser/brave_content_settings_utils_unittest.cc",
@@ -717,6 +718,7 @@ if (!is_android) {
       "//brave/components/brave_rewards/browser/test/rewards_publisher_browsertest.cc",
       "//brave/components/brave_rewards/browser/test/rewards_state_browsertest.cc",
       "//brave/components/brave_shields/browser/https_everywhere_service_browsertest.cc",
+      "//brave/components/brave_shields/browser/test_filters_provider.cc",
       "//brave/components/content_settings/renderer/brave_content_settings_agent_impl_autoplay_browsertest.cc",
       "//brave/components/content_settings/renderer/brave_content_settings_agent_impl_browsertest.cc",
       "//brave/components/l10n/browser/locale_helper_mock.cc",
diff --git a/test/base/testing_brave_browser_process.cc b/test/base/testing_brave_browser_process.cc
index d95ab1ad1bf4..0dda32d06a4a 100644
--- a/test/base/testing_brave_browser_process.cc
+++ b/test/base/testing_brave_browser_process.cc
@@ -49,18 +49,6 @@ brave_shields::AdBlockService* TestingBraveBrowserProcess::ad_block_service() {
   return ad_block_service_.get();
 }
 
-brave_shields::AdBlockCustomFiltersService*
-TestingBraveBrowserProcess::ad_block_custom_filters_service() {
-  NOTREACHED();
-  return nullptr;
-}
-
-brave_shields::AdBlockRegionalServiceManager*
-TestingBraveBrowserProcess::ad_block_regional_service_manager() {
-  NOTREACHED();
-  return nullptr;
-}
-
 #if BUILDFLAG(ENABLE_EXTENSIONS)
 brave_component_updater::ExtensionWhitelistService*
 TestingBraveBrowserProcess::extension_whitelist_service() {
diff --git a/test/base/testing_brave_browser_process.h b/test/base/testing_brave_browser_process.h
index 9a4d5caff1a1..5e034a09e627 100644
--- a/test/base/testing_brave_browser_process.h
+++ b/test/base/testing_brave_browser_process.h
@@ -42,10 +42,6 @@ class TestingBraveBrowserProcess : public BraveBrowserProcess {
   // BraveBrowserProcess overrides:
   void StartBraveServices() override;
   brave_shields::AdBlockService* ad_block_service() override;
-  brave_shields::AdBlockCustomFiltersService* ad_block_custom_filters_service()
-      override;
-  brave_shields::AdBlockRegionalServiceManager*
-  ad_block_regional_service_manager() override;
 #if BUILDFLAG(ENABLE_EXTENSIONS)
   brave_component_updater::ExtensionWhitelistService*
   extension_whitelist_service() override;