optimization: don't parse yt metadata (or fetch transcript) until an …

…ai chat message is sent by the user

components/ai_chat/content/browser/ai_chat_tab_helper.cc

@@ -154,10 +154,6 @@ void AIChatTabHelper::DidFinishNavigation(
   is_same_document_navigation_ = navigation_handle->IsSameDocument();
   pending_navigation_id_ = navigation_handle->GetNavigationId();
 
-  // Re-assess whether we get content from subresource interception on every
-  // navigation (same-document or not).
-  SetIsContentSubresourceDependent(false);
-
   // Experimentally only call |OnNewPage| for same-page navigations _if_
   // it results in a page title change (see |TtileWasSet|).
   if (!is_same_document_navigation_) {
@@ -219,23 +215,11 @@ void AIChatTabHelper::OnFaviconUpdated(
 }
 
 // mojom::PageContentExtractorHost
-void AIChatTabHelper::OnInterceptedPageContentChanged(
-    mojom::PageContentPtr content) {
+void AIChatTabHelper::OnInterceptedPageContentChanged() {
   DVLOG(2) << __func__;
-
-  // TODO(petemill): Only accept basic content string - no fetching or even json
-  // parsing. Store in local variable until getpagecontent is called. This is
-  // performance optimization so that we're not doing extra work when there's no
-  // active conversation. We still need to store this data for inactive
-  // conversations so that if a conversation is opened for the current
-  // navigation then we are able to retrieve the content that's only accessible
-  // via subresource interception.
-
-  // Stop reading page content from document, use subresource instead from now
-  // on.
-  SetIsContentSubresourceDependent(true);
   // Maybe mark that the page changed, if we didn't detect it already via title
-  // change after a same-page navigation.
+  // change after a same-page navigation. This is the main benefit of this
+  // function.
   if (is_same_document_navigation_) {
     DVLOG(2) << "Same document navigation detected new \"page\" - calling "
                 "OnNewPage()";
@@ -245,20 +229,6 @@ void AIChatTabHelper::OnInterceptedPageContentChanged(
     // Don't respond to further TitleWasSet
     is_same_document_navigation_ = false;
   }
-  // Fetch new page text and update the conversation
-  // TODO(petemill): use method with WeakPtr because FetchPageContent might hold
-  // on to callback after TabHelper destroyed.
-  GetPageContentCallback cb = base::BindOnce(
-      [](AIChatTabHelper* instance, const int64_t navigation_id,
-         std::string content, bool success, std::string invalidation_token) {
-        if (instance->pending_navigation_id_ != navigation_id) {
-          DVLOG(1) << "Ignoring content update for stale navigation id";
-          return;
-        }
-        instance->OnPageContentUpdated(content, success, invalidation_token);
-      },
-      base::Unretained(this), pending_navigation_id_);
-  FetchPageContent(web_contents(), std::move(content), std::move(cb));
 }
 
 // ai_chat::ConversationDriver

components/ai_chat/content/browser/ai_chat_tab_helper.h

@@ -51,8 +51,7 @@ class AIChatTabHelper : public content::WebContentsObserver,
   void SetOnPDFA11yInfoLoadedCallbackForTesting(base::OnceClosure cb);
 
   // mojom::PageContentExtractorHost
-  void OnInterceptedPageContentChanged(
-      mojom::PageContentPtr page_content) override;
+  void OnInterceptedPageContentChanged() override;
 
  private:
   friend class content::WebContentsUserData<AIChatTabHelper>;

components/ai_chat/content/browser/page_content_fetcher.cc

@@ -523,17 +523,4 @@ void FetchPageContent(content::WebContents* web_contents,
   fetcher->Start(std::move(extractor), invalidation_token, std::move(callback));
 }
 
-void FetchPageContent(content::WebContents* web_contents,
-                      mojom::PageContentPtr content_hint,
-                      FetchPageContentCallback callback) {
-  auto* loader = web_contents->GetBrowserContext()
-                     ->GetDefaultStoragePartition()
-                     ->GetURLLoaderFactoryForBrowserProcess()
-                     .get();
-  auto* fetcher = new PageContentFetcher(loader);
-  // Invalidation token is blank because having PageContent implies content is
-  // new.
-  fetcher->OnTabContentResult(std::move(callback), "", std::move(content_hint));
-}
-
 }  // namespace ai_chat

components/ai_chat/content/browser/page_content_fetcher.h

@@ -31,9 +31,6 @@ void FetchPageContent(content::WebContents* web_contents,
                       FetchPageContentCallback callback,
                       scoped_refptr<network::SharedURLLoaderFactory>
                           url_loader_factory = nullptr);
-void FetchPageContent(content::WebContents* web_contents,
-                      mojom::PageContentPtr content_hint,
-                      FetchPageContentCallback callback);
 
 }  // namespace ai_chat
 

components/ai_chat/core/browser/conversation_driver.cc

@@ -426,14 +426,6 @@ void ConversationDriver::GeneratePageContent(GetPageContentCallback callback) {
   DCHECK(is_conversation_active_)
       << "UI shouldn't allow operations for an inactive conversation";
 
-  if (is_content_subresource_dependent_ && !article_text_.empty()) {
-    // If the content is pushed from renderer, then we possibly do not have
-    // a way to fetch it on-demand. So we provide the cached content instead.
-    std::move(callback).Run(article_text_, is_video_,
-                            content_invalidation_token_);
-    return;
-  }
-
   // Only perform a fetch once at a time, and then use the results from
   // an in-progress operation.
   if (is_page_text_fetch_in_progress_) {

components/ai_chat/core/browser/conversation_driver.h

@@ -157,12 +157,6 @@ class ConversationDriver {
   // is expected.
   void OnNewPage(int64_t navigation_id);
 
-  // Set the flag to indicate that the page content can not be fetched on-demand
-  // and is dependent on intercepted subresources.
-  void SetIsContentSubresourceDependent(bool is_content_subresource_dependent) {
-    is_content_subresource_dependent_ = is_content_subresource_dependent;
-  }
-
  private:
   void InitEngine();
   void OnUserOptedIn();
@@ -223,7 +217,6 @@ class ConversationDriver {
   std::string article_text_;
   std::string content_invalidation_token_;
   bool is_page_text_fetch_in_progress_ = false;
-  bool is_content_subresource_dependent_ = false;
   std::unique_ptr<base::OneShotEvent> on_page_text_fetch_complete_;
 
   bool is_request_in_progress_ = false;

components/ai_chat/core/common/mojom/page_content_extractor.mojom

@@ -33,5 +33,8 @@ interface PageContentExtractor {
 // Allows the renderer to notify the browser process of meaningful changes to
 // the content.
 interface PageContentExtractorHost {
-  OnInterceptedPageContentChanged(PageContent page_content);
+  // We don't send page content here due to an optimization for the majority of
+  // renderers without active AIChat conversations. We wait until the host
+  // requests it via PageContentExtractor.ExtractPageContent.
+  OnInterceptedPageContentChanged();
 };

components/ai_chat/renderer/ai_chat_resource_sniffer_throttle_delegate.h

@@ -6,14 +6,22 @@
 #ifndef BRAVE_COMPONENTS_AI_CHAT_RENDERER_AI_CHAT_RESOURCE_SNIFFER_THROTTLE_DELEGATE_H_
 #define BRAVE_COMPONENTS_AI_CHAT_RENDERER_AI_CHAT_RESOURCE_SNIFFER_THROTTLE_DELEGATE_H_
 
-#include "brave/components/ai_chat/core/common/mojom/page_content_extractor.mojom.h"
+#include <memory>
+#include <string>
 
 namespace ai_chat {
 
 class AIChatResourceSnifferThrottleDelegate {
  public:
+  enum class InterceptedContentType {
+    kYouTubeMetadataString,
+  };
+  struct InterceptedContent {
+    InterceptedContentType type;
+    std::string content;
+  };
   virtual void OnInterceptedPageContentChanged(
-      mojom::PageContentPtr content) = 0;
+      std::unique_ptr<InterceptedContent> content) = 0;
 
  protected:
   virtual ~AIChatResourceSnifferThrottleDelegate() = default;

components/ai_chat/renderer/ai_chat_resource_sniffer_throttle_unittest.cc

@@ -23,7 +23,7 @@
 #include "services/network/public/mojom/url_response_head.mojom.h"
 #include "services/network/test/test_url_loader_client.h"
 #include "services/network/test/test_url_loader_factory.h"
-#include "testing/gmock/include/gmock/gmock-matchers.h"
+#include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/blink/public/common/loader/url_loader_throttle.h"
 #include "third_party/googletest/src/googletest/include/gtest/gtest.h"
@@ -89,18 +89,17 @@ class MojoDataPipeSender {
 class MockAIChatResourceSnifferThrottleDelegate
     : public AIChatResourceSnifferThrottleDelegate {
  public:
-  MockAIChatResourceSnifferThrottleDelegate() = default;
-  ~MockAIChatResourceSnifferThrottleDelegate() override = default;
-
-  void OnInterceptedPageContentChanged(mojom::PageContentPtr content) override {
-    ASSERT_TRUE(content->content->is_content_url());
-    ASSERT_EQ(content->type, mojom::PageContentType::VideoTranscriptYouTube);
-    OnInterceptedPageContentChanged_Data(
-        content->content->get_content_url().spec());
-  }
-
   MOCK_METHOD(void, OnInterceptedPageContentChanged_Data, (std::string));
 
+  void OnInterceptedPageContentChanged(
+      std::unique_ptr<AIChatResourceSnifferThrottleDelegate::InterceptedContent>
+          content) override {
+    ASSERT_EQ(content->type,
+              AIChatResourceSnifferThrottleDelegate::InterceptedContentType::
+                  kYouTubeMetadataString);
+    OnInterceptedPageContentChanged_Data(content->content);
+  }
+
   base::WeakPtrFactory<MockAIChatResourceSnifferThrottleDelegate> weak_factory_{
       this};
 };
@@ -281,30 +280,19 @@ TEST_F(AIChatResourceSnifferThrottleTest, DoesNotThrottleNonHTTP) {
 }
 
 TEST_F(AIChatResourceSnifferThrottleTest, Body_NonJson) {
-  // PNG
-  InterceptBodyRequestFor("\x89PNG\x0D\x0A\x1A\x0A");
-  EXPECT_CALL(ai_chat_throttle_delegate_, OnInterceptedPageContentChanged_Data)
-      .Times(0);
-}
-
-TEST_F(AIChatResourceSnifferThrottleTest, Body_InvalidJson) {
-  InterceptBodyRequestFor("{");
-  EXPECT_CALL(ai_chat_throttle_delegate_, OnInterceptedPageContentChanged_Data)
-      .Times(0);
-}
-
-TEST_F(AIChatResourceSnifferThrottleTest, Body_ValidNonYTJson) {
-  InterceptBodyRequestFor(R"({"captions": []})");
-  EXPECT_CALL(ai_chat_throttle_delegate_, OnInterceptedPageContentChanged_Data)
-      .Times(0);
+  // AIChatResourceSnifferThrottle doesn't parse the json as an optimization
+  // since it might not get used until an AIChat conversation message is about
+  // to be sent, so any body content should be passed to the delegate, we don't
+  // need to test for valid JSON
+  std::string body = "\x89PNG\x0D\x0A\x1A\x0A";
+  EXPECT_CALL(ai_chat_throttle_delegate_,
+              OnInterceptedPageContentChanged_Data(body))
+      .Times(1);
+  InterceptBodyRequestFor(body);
 }
 
 TEST_F(AIChatResourceSnifferThrottleTest, Body_ValidYTJson) {
-  EXPECT_CALL(
-      ai_chat_throttle_delegate_,
-      OnInterceptedPageContentChanged_Data("https://www.example.com/caption1"))
-      .Times(1);
-  InterceptBodyRequestFor(R"({
+  std::string body = R"({
     "captions": {
       "playerCaptionsTracklistRenderer": {
         "captionTracks": [
@@ -314,37 +302,20 @@ TEST_F(AIChatResourceSnifferThrottleTest, Body_ValidYTJson) {
         ]
       }
     }
-  })");
-  mojom::PageContentPtr expected_content = mojom::PageContent::New();
-  expected_content->type = mojom::PageContentType::VideoTranscriptYouTube;
-  expected_content->content = mojom::PageContentData::NewContentUrl(GURL());
+  })";
+  EXPECT_CALL(ai_chat_throttle_delegate_,
+              OnInterceptedPageContentChanged_Data(body))
+      .Times(1);
+  InterceptBodyRequestFor(body);
 }
 
-TEST_F(AIChatResourceSnifferThrottleTest, Abort_NoBodyPipe) {
-  GURL url("https://www.youtube.com/youtubei/v1/player");
-  auto throttle = MaybeCreateThrottleForUrl(url);
-  auto delegate = std::make_unique<MockDelegate>();
-  throttle->set_delegate(delegate.get());
-
-  auto response_head = network::mojom::URLResponseHead::New();
-  bool defer = false;
-  throttle->WillProcessResponse(url, response_head.get(), &defer);
-  EXPECT_FALSE(defer);
-  EXPECT_TRUE(delegate->is_intercepted());
-
-  // Send the body
-  std::string body = "This should be long enough to complete sniffing.";
-  body.resize(1024, 'a');
-  delegate->LoadResponseBody(body);
-  task_environment_.RunUntilIdle();
-
-  // Release a pipe for the body on the receiver side.
-  delegate->destination_loader_client()->response_body_release();
-  task_environment_.RunUntilIdle();
-
-  // Calling OnComplete should not crash.
-  delegate->CompleteResponse();
-  task_environment_.RunUntilIdle();
+TEST_F(AIChatResourceSnifferThrottleTest, LongBody) {
+  std::string body = "This should be long enough...";
+  body.resize(2048, 'a');
+  EXPECT_CALL(ai_chat_throttle_delegate_,
+              OnInterceptedPageContentChanged_Data(body))
+      .Times(1);
+  InterceptBodyRequestFor(body);
 }
 
 }  // namespace ai_chat

components/ai_chat/renderer/ai_chat_resource_sniffer_url_loader.cc

@@ -5,15 +5,14 @@
 
 #include "brave/components/ai_chat/renderer/ai_chat_resource_sniffer_url_loader.h"
 
+#include <memory>
 #include <string>
 #include <utility>
 
 #include "base/json/json_reader.h"
 #include "base/logging.h"
 #include "base/types/expected.h"
 #include "base/values.h"
-#include "brave/components/ai_chat/core/common/mojom/page_content_extractor.mojom.h"
-#include "brave/components/ai_chat/renderer/yt_util.h"
 #include "brave/components/body_sniffer/body_sniffer_url_loader.h"
 #include "mojo/public/cpp/bindings/self_owned_receiver.h"
 
@@ -23,32 +22,6 @@ namespace {
 
 constexpr uint32_t kReadBufferSize = 37000;  // average subresource size
 
-std::optional<std::string> GetCaptionTrackUrl(std::string& body) {
-  if (!body.size()) {
-    return std::nullopt;
-  }
-
-  auto result_value =
-      base::JSONReader::ReadAndReturnValueWithError(body, base::JSON_PARSE_RFC);
-
-  if (!result_value.has_value() || result_value->is_string()) {
-    VLOG(1) << __func__ << ": parsing error: " << result_value.ToString();
-    return std::nullopt;
-  } else if (!result_value->is_dict()) {
-    VLOG(1) << __func__ << ": parsing error: not a dict";
-    return std::nullopt;
-  }
-
-  auto* caption_tracks = result_value->GetDict().FindListByDottedPath(
-      "captions.playerCaptionsTracklistRenderer.captionTracks");
-  if (!caption_tracks) {
-    VLOG(1) << __func__ << ": no caption tracks found";
-    return std::nullopt;
-  }
-
-  return ChooseCaptionTrackUrl(caption_tracks);
-}
-
 }  // namespace
 
 // static
@@ -115,20 +88,14 @@ void AIChatResourceSnifferURLLoader::OnBodyWritable(MojoResult r) {
 void AIChatResourceSnifferURLLoader::CompleteLoading(std::string body) {
   DVLOG(4) << __func__ << ": got body length: " << body.size()
            << " for url: " << response_url_.spec();
-
-  auto maybe_caption_url = GetCaptionTrackUrl(body);
-
-  if (maybe_caption_url.has_value()) {
-    GURL caption_url = response_url_.Resolve(maybe_caption_url.value());
-    if (caption_url.is_valid()) {
-      mojom::PageContentPtr content_update = mojom::PageContent::New();
-      content_update->type = mojom::PageContentType::VideoTranscriptYouTube;
-      content_update->content =
-          mojom::PageContentData::NewContentUrl(GURL(caption_url));
-      delegate_->OnInterceptedPageContentChanged(std::move(content_update));
-    }
+  if (!body.empty()) {
+    auto content = std::make_unique<
+        AIChatResourceSnifferThrottleDelegate::InterceptedContent>();
+    content->type = AIChatResourceSnifferThrottleDelegate::
+        InterceptedContentType::kYouTubeMetadataString;
+    content->content = body;
+    delegate_->OnInterceptedPageContentChanged(std::move(content));
   }
-
   body_sniffer::BodySnifferURLLoader::CompleteLoading(std::move(body));
 }