Remove UserAgentOverrideExperiment and related code

This experiment is now expired and was conducted to study the
performance effect of various checks on the User-Agent string
overrides.

This CL is a major cleanup, expect minor cleanup CLs as follow ups to
this.

Bug: 1336959
Change-Id: Id7d14c62bb421163abda83b099eb6e9bef0779b7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4192069
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Jonathan Njeunje <njeunje@chromium.org>
Reviewed-by: Joe Mason <joenotcharles@google.com>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: James Maclean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1099444}

chrome/browser/page_load_metrics/page_load_metrics_browsertest.cc

@@ -67,8 +67,6 @@
 #include "components/page_load_metrics/browser/page_load_tracker.h"
 #include "components/prefs/pref_service.h"
 #include "components/sessions/content/content_test_helper.h"
-#include "components/sessions/core/serialized_navigation_entry.h"
-#include "components/sessions/core/serialized_navigation_entry_test_helper.h"
 #include "components/ukm/test_ukm_recorder.h"
 #include "content/public/browser/back_forward_cache.h"
 #include "content/public/browser/browser_thread.h"
@@ -102,7 +100,6 @@
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/blink/public/common/chrome_debug_urls.h"
 #include "third_party/blink/public/common/features.h"
-#include "third_party/blink/public/common/user_agent/user_agent_metadata.h"
 #include "third_party/blink/public/mojom/use_counter/metrics/css_property_id.mojom.h"
 #include "third_party/blink/public/mojom/use_counter/metrics/web_feature.mojom.h"
 #include "ui/gfx/geometry/size.h"
@@ -187,8 +184,7 @@ class PageLoadMetricsBrowserTest : public InProcessBrowserTest {
   PageLoadMetricsBrowserTest() {
     scoped_feature_list_.InitWithFeatures(
         {ukm::kUkmFeature, blink::features::kPortals,
-         blink::features::kPortalsCrossOrigin,
-         blink::features::kUserAgentOverrideExperiment},
+         blink::features::kPortalsCrossOrigin},
         {});
   }
 
@@ -2293,107 +2289,6 @@ IN_PROC_BROWSER_TEST_F(PageLoadMetricsBrowserTest, LoadingMetrics) {
   waiter->Wait();
 }
 
-IN_PROC_BROWSER_TEST_F(PageLoadMetricsBrowserTest,
-                       UseCounterUserAgentOverride) {
-  ASSERT_TRUE(embedded_test_server()->Start());
-
-  content::WebContents* web_contents =
-      browser()->tab_strip_model()->GetActiveWebContents();
-  std::string original_ua = embedder_support::GetUserAgent();
-  std::string ua_no_substring = "foo";
-  std::string ua_prefix = "foo" + original_ua;
-  std::string ua_suffix = original_ua + "foo";
-
-  {
-    base::HistogramTester histogram;
-    web_contents->SetUserAgentOverride(
-        blink::UserAgentOverride::UserAgentOnly(ua_no_substring), false);
-    web_contents->GetController()
-        .GetLastCommittedEntry()
-        ->SetIsOverridingUserAgent(true);
-    auto waiter = CreatePageLoadMetricsTestWaiter("waiter");
-    waiter->AddUseCounterFeatureExpectation({
-        blink::mojom::UseCounterFeatureType::kUserAgentOverride,
-        blink::UserAgentOverride::UserAgentOverriden,
-    });
-    ASSERT_TRUE(ui_test_utils::NavigateToURL(
-        browser(), embedded_test_server()->GetURL("/empty.html")));
-    content::EvalJsResult result = EvalJs(web_contents, "navigator.userAgent;");
-    waiter->Wait();
-    NavigateToUntrackedUrl();
-    content::FetchHistogramsFromChildProcesses();
-    // Expect 2; one in the navigation stack and one in the renderer
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverriden, 2);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSubstring, 0);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSuffix, 0);
-  }
-
-  {
-    base::HistogramTester histogram;
-    web_contents->SetUserAgentOverride(
-        blink::UserAgentOverride::UserAgentOnly(ua_prefix), false);
-    web_contents->GetController()
-        .GetLastCommittedEntry()
-        ->SetIsOverridingUserAgent(true);
-    auto waiter = CreatePageLoadMetricsTestWaiter("waiter");
-    waiter->AddUseCounterFeatureExpectation({
-        blink::mojom::UseCounterFeatureType::kUserAgentOverride,
-        blink::UserAgentOverride::UserAgentOverrideSubstring,
-    });
-    ASSERT_TRUE(ui_test_utils::NavigateToURL(
-        browser(), embedded_test_server()->GetURL("/empty.html")));
-    content::EvalJsResult result = EvalJs(web_contents, "navigator.userAgent;");
-    waiter->Wait();
-    NavigateToUntrackedUrl();
-    content::FetchHistogramsFromChildProcesses();
-    // Expect 2; one in the navigation stack and one in the renderer
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverriden, 0);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSubstring, 2);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSuffix, 0);
-  }
-  {
-    base::HistogramTester histogram;
-    web_contents->SetUserAgentOverride(
-        blink::UserAgentOverride::UserAgentOnly(ua_suffix), false);
-    web_contents->GetController()
-        .GetLastCommittedEntry()
-        ->SetIsOverridingUserAgent(true);
-    auto waiter = CreatePageLoadMetricsTestWaiter("waiter");
-    waiter->AddUseCounterFeatureExpectation({
-        blink::mojom::UseCounterFeatureType::kUserAgentOverride,
-        blink::UserAgentOverride::UserAgentOverrideSuffix,
-    });
-    ASSERT_TRUE(ui_test_utils::NavigateToURL(
-        browser(), embedded_test_server()->GetURL("/empty.html")));
-    content::EvalJsResult result = EvalJs(web_contents, "navigator.userAgent;");
-    waiter->Wait();
-    NavigateToUntrackedUrl();
-    content::FetchHistogramsFromChildProcesses();
-    // Expect 2; one in the navigation stack and one in the renderer
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverriden, 0);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSubstring, 0);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSuffix, 2);
-  }
-}
-
 class SessionRestorePageLoadMetricsBrowserTest
     : public PageLoadMetricsBrowserTest {
  public:

components/page_load_metrics/browser/observers/use_counter_page_load_metrics_observer.cc

@@ -17,8 +17,6 @@ using UkmFeatureList = UseCounterMetricsRecorder::UkmFeatureList;
 using WebFeature = blink::mojom::WebFeature;
 using CSSSampleId = blink::mojom::CSSSampleId;
 using PermissionsPolicyFeature = blink::mojom::PermissionsPolicyFeature;
-using UserAgentOverrideHistogram =
-    blink::UserAgentOverride::UserAgentOverrideHistogram;
 
 #define FEATURE_HISTOGRAM_NAME(name, is_in_fenced_frames)     \
   is_in_fenced_frames ? "Blink.UseCounter.FencedFrames." name \
@@ -89,11 +87,6 @@ UseCounterMetricsRecorder::UseCounterMetricsRecorder(bool is_in_fenced_frame)
       uma_permissions_policy_header2_(
           AtMostOnceEnumUmaDeferrer<blink::mojom::PermissionsPolicyFeature>(
               FEATURE_HISTOGRAM_NAME("PermissionsPolicy.Header2",
-                                     is_in_fenced_frame))),
-      uma_user_agent_override_(
-          AtMostOnceEnumUmaDeferrer<
-              blink::UserAgentOverride::UserAgentOverrideHistogram>(
-              FEATURE_HISTOGRAM_NAME("UserAgentOverride",
                                      is_in_fenced_frame))) {}
 
 UseCounterMetricsRecorder::~UseCounterMetricsRecorder() = default;
@@ -135,7 +128,6 @@ void UseCounterMetricsRecorder::DisableDeferAndFlush() {
   uma_permissions_policy_violation_enforce_.DisableDeferAndFlush();
   uma_permissions_policy_allow2_.DisableDeferAndFlush();
   uma_permissions_policy_header2_.DisableDeferAndFlush();
-  uma_user_agent_override_.DisableDeferAndFlush();
 }
 
 void UseCounterMetricsRecorder::RecordOrDeferUseCounterFeature(
@@ -179,10 +171,6 @@ void UseCounterMetricsRecorder::RecordOrDeferUseCounterFeature(
       uma_permissions_policy_allow2_.RecordOrDefer(
           static_cast<PermissionsPolicyFeature>(feature.value()));
       break;
-    case FeatureType::kUserAgentOverride:
-      uma_user_agent_override_.RecordOrDefer(
-          static_cast<UserAgentOverrideHistogram>(feature.value()));
-      break;
   }
 }
 

components/page_load_metrics/browser/observers/use_counter_page_load_metrics_observer.h

@@ -77,9 +77,6 @@ class UseCounterMetricsRecorder {
 
   AtMostOnceEnumUmaDeferrer<blink::mojom::PermissionsPolicyFeature>
       uma_permissions_policy_header2_;
-  AtMostOnceEnumUmaDeferrer<
-      blink::UserAgentOverride::UserAgentOverrideHistogram>
-      uma_user_agent_override_;
 
   // To keep tracks of which features have been measured.
   std::bitset<static_cast<size_t>(blink::mojom::WebFeature::kNumberOfFeatures)>

components/page_load_metrics/browser/observers/use_counter_page_load_metrics_observer_unittest.cc

@@ -50,8 +50,6 @@ const char* GetUseCounterHistogramName(
         return "Blink.UseCounter.FencedFrames.PermissionsPolicy.Header2";
       case FeatureType::kPermissionsPolicyIframeAttribute:
         return "Blink.UseCounter.FencedFrames.PermissionsPolicy.Allow2";
-      case FeatureType::kUserAgentOverride:
-        return "Blink.UseCounter.FencedFrames.UserAgentOverride";
     }
   } else {
     if (is_in_main_frame) {
@@ -71,8 +69,6 @@ const char* GetUseCounterHistogramName(
         return "Blink.UseCounter.PermissionsPolicy.Header2";
       case FeatureType::kPermissionsPolicyIframeAttribute:
         return "Blink.UseCounter.PermissionsPolicy.Allow2";
-      case FeatureType::kUserAgentOverride:
-        return "Blink.UseCounter.UserAgentOverride";
     }
   }
 }

content/browser/renderer_host/navigation_request.cc

@@ -345,31 +345,6 @@ bool DoesHeaderContainClientHint(
   return headers.GetHeader(header, &value) && value == "?1";
 }
 
-void LogUserAgentOverrideHistogram(const std::string& user_agent) {
-  std::string ua_original = GetContentClient()->browser()->GetUserAgent();
-  base::UmaHistogramEnumeration("Navigation.UserAgentStringType",
-                                UserAgentStringType::kOverriden);
-
-  if (!base::FeatureList::IsEnabled(
-          blink::features::kUserAgentOverrideExperiment)) {
-    return;
-  }
-
-  auto it = user_agent.find(ua_original);
-  blink::UserAgentOverride::UserAgentOverrideHistogram histogram =
-      blink::UserAgentOverride::UserAgentOverrideHistogram::UserAgentOverriden;
-  if (it == 0) {
-    histogram = blink::UserAgentOverride::UserAgentOverrideHistogram::
-        UserAgentOverrideSuffix;
-  } else if (it != std::string::npos) {
-    histogram = blink::UserAgentOverride::UserAgentOverrideHistogram::
-        UserAgentOverrideSubstring;
-  }
-
-  base::UmaHistogramEnumeration(
-      blink::UserAgentOverride::kUserAgentOverrideHistogram, histogram);
-}
-
 // Computes the value that should be set for the User-Agent header, based on the
 // values of relevant headers like Sec-CH-UA-Reduced or Sec-CH-UA-Full.  If
 // `user_agent_override` is non-empty, `user_agent_override` is returned as the
@@ -378,7 +353,8 @@ std::string ComputeUserAgentValue(const net::HttpRequestHeaders& headers,
                                   const std::string& user_agent_override,
                                   content::BrowserContext* context) {
   if (!user_agent_override.empty()) {
-    LogUserAgentOverrideHistogram(user_agent_override);
+    base::UmaHistogramEnumeration("Navigation.UserAgentStringType",
+                                  UserAgentStringType::kOverriden);
     return user_agent_override;
   }
 

content/browser/web_contents/web_contents_impl_browsertest.cc

@@ -2549,94 +2549,6 @@ IN_PROC_BROWSER_TEST_F(WebContentsImplBrowserTest, UserAgentOverride) {
             EvalJs(shell()->web_contents(), "document.body.textContent;"));
 }
 
-class WebContentsImplBrowserTestUserAgentOverrideSubstring
-    : public WebContentsImplBrowserTest {
- public:
-  void SetUp() override {
-    scoped_feature_list_.Reset();
-    scoped_feature_list_.InitAndEnableFeature(
-        blink::features::kUserAgentOverrideExperiment);
-    WebContentsImplBrowserTest::SetUp();
-  }
-};
-
-// Verify UserAgentOverride histograms
-IN_PROC_BROWSER_TEST_F(WebContentsImplBrowserTestUserAgentOverrideSubstring,
-                       UserAgentOverrideHistogram) {
-  ASSERT_TRUE(embedded_test_server()->Start());
-  const std::string kHeaderPath =
-      std::string("/echoheader?") + net::HttpRequestHeaders::kUserAgent;
-  const GURL kUrl(embedded_test_server()->GetURL(kHeaderPath));
-  EXPECT_TRUE(NavigateToURL(shell(), kUrl));
-
-  std::string original_ua = ShellContentBrowserClient::Get()->GetUserAgent();
-  std::string ua_no_substring = "foo";
-  std::string ua_prefix = "foo" + original_ua;
-  std::string ua_suffix = original_ua + "foo";
-  {
-    base::HistogramTester histogram;
-    shell()->web_contents()->SetUserAgentOverride(
-        blink::UserAgentOverride::UserAgentOnly(ua_no_substring), false);
-    shell()
-        ->web_contents()
-        ->GetController()
-        .GetLastCommittedEntry()
-        ->SetIsOverridingUserAgent(true);
-    EXPECT_TRUE(NavigateToURL(shell(), kUrl));
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverriden, 1);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSubstring, 0);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSuffix, 0);
-  }
-
-  {
-    base::HistogramTester histogram;
-    shell()->web_contents()->SetUserAgentOverride(
-        blink::UserAgentOverride::UserAgentOnly(ua_prefix), false);
-    shell()
-        ->web_contents()
-        ->GetController()
-        .GetLastCommittedEntry()
-        ->SetIsOverridingUserAgent(true);
-    EXPECT_TRUE(NavigateToURL(shell(), kUrl));
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverriden, 0);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSubstring, 1);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSuffix, 0);
-  }
-
-  {
-    base::HistogramTester histogram;
-    shell()->web_contents()->SetUserAgentOverride(
-        blink::UserAgentOverride::UserAgentOnly(ua_suffix), false);
-    shell()
-        ->web_contents()
-        ->GetController()
-        .GetLastCommittedEntry()
-        ->SetIsOverridingUserAgent(true);
-    EXPECT_TRUE(NavigateToURL(shell(), kUrl));
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverriden, 0);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSubstring, 0);
-    histogram.ExpectBucketCount(
-        blink::UserAgentOverride::kUserAgentOverrideHistogram,
-        blink::UserAgentOverride::UserAgentOverrideSuffix, 1);
-  }
-}
-
 // Verifies the user-agent string may be changed in DidStartNavigation().
 IN_PROC_BROWSER_TEST_F(WebContentsImplBrowserTest,
                        SetUserAgentOverrideFromDidStartNavigation) {

extensions/browser/guest_view/web_view/web_view_apitest.cc

@@ -930,10 +930,8 @@ class WebViewAPITestUserAgentOverride
     : public WebViewAPITest {
  public:
   void SetUp() override {
-    scoped_feature_list_.InitWithFeatures(
-        {blink::features::kUserAgentOverrideExperiment,
-         blink::features::kUACHOverrideBlank},
-        {});
+    scoped_feature_list_.InitWithFeatures({blink::features::kUACHOverrideBlank},
+                                          {});
     WebViewAPITest::SetUp();
   }
 
@@ -959,13 +957,8 @@ IN_PROC_BROWSER_TEST_F(WebViewAPITestUserAgentOverride, TestSetUserAgentOverride
   https_server.SetSSLConfig(
       net::test_server::EmbeddedTestServer::CERT_COMMON_NAME_IS_DOMAIN);
   ASSERT_TRUE(https_server.Start());
-  base::HistogramTester histogram;
   test_config_.SetByDottedPath(kTestServerPort, https_server.port());
   RunTest("testSetUserAgentOverride", "web_view/apitest");
-  content::FetchHistogramsFromChildProcesses();
-  histogram.ExpectBucketCount(
-      blink::UserAgentOverride::kUserAgentOverrideHistogram,
-      blink::UserAgentOverride::UserAgentOverriden, 1);
 }
 
 }  // namespace extensions

third_party/blink/common/use_counter/use_counter_feature.cc

@@ -40,11 +40,6 @@ bool UseCounterFeature::IsValid() const {
       return value_ < static_cast<UseCounterFeature::EnumValue>(
                           mojom::PermissionsPolicyFeature::kMaxValue) +
                           1;
-    case mojom::UseCounterFeatureType::kUserAgentOverride:
-      return value_ < static_cast<UseCounterFeature::EnumValue>(
-                          blink::UserAgentOverride::UserAgentOverrideHistogram::
-                              kMaxValue) +
-                          1;
   }
 }
 

third_party/blink/common/use_counter/use_counter_feature_mojom_traits.cc

@@ -30,8 +30,6 @@ bool IsReservedFeature(const blink::UseCounterFeature& feature) {
       return feature.value() ==
              static_cast<blink::UseCounterFeature::EnumValue>(
                  blink::mojom::PermissionsPolicyFeature::kNotFound);
-    case blink::mojom::UseCounterFeatureType::kUserAgentOverride:
-      return false;
   }
 }
 }  // namespace