Remove top-of-stack-only experimental AdTagging code

The experiment is being abandoned, so this cl removes the code for it.

Bug: 1161316
Change-Id: I4d5091982874f1c36afbf21c6e81eee867e08ed9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2597853Reviewed-by: Josh Karlin <jkarlin@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Alex Turner <alexmt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840281}

third_party/blink/renderer/core/frame/ad_tracker.cc

@@ -51,11 +51,6 @@ namespace features {
 // the currently running stack is ad related.
 const base::Feature kAsyncStackAdTagging{"AsyncStackAdTagging",
                                          base::FEATURE_ENABLED_BY_DEFAULT};
-
-// Controls whether the AdTracker analyzes the bottom and top of the stack or
-// just the top of the stack when detecting ads.
-const base::Feature kTopOfStackAdTagging{"TopOfStackAdTagging",
-                                         base::FEATURE_DISABLED_BY_DEFAULT};
 }  // namespace features
 
 // static
@@ -82,9 +77,7 @@ bool AdTracker::IsAdScriptExecutingInDocument(Document* document,
 AdTracker::AdTracker(LocalFrame* local_root)
     : local_root_(local_root),
       async_stack_enabled_(
-          base::FeatureList::IsEnabled(features::kAsyncStackAdTagging)),
-      top_of_stack_only_(
-          base::FeatureList::IsEnabled(features::kTopOfStackAdTagging)) {
+          base::FeatureList::IsEnabled(features::kAsyncStackAdTagging)) {
   local_root_->GetProbeSink()->AddAdTracker(this);
 }
 
@@ -149,9 +142,6 @@ void AdTracker::WillExecuteScript(ExecutionContext* execution_context,
     }
   }
 
-  if (top_of_stack_only_)
-    return;
-
   if (!should_track_with_id)
     is_ad = IsKnownAdScript(execution_context, script_url);
 
@@ -161,9 +151,6 @@ void AdTracker::WillExecuteScript(ExecutionContext* execution_context,
 }
 
 void AdTracker::DidExecuteScript() {
-  if (top_of_stack_only_)
-    return;
-
   if (stack_frame_is_ad_.back()) {
     DCHECK_LT(0u, num_ads_in_stack_);
     num_ads_in_stack_ -= 1;

third_party/blink/renderer/core/frame/ad_tracker.h

@@ -30,7 +30,6 @@ class ExecuteScript;
 
 namespace features {
 CORE_EXPORT extern const base::Feature kAsyncStackAdTagging;
-CORE_EXPORT extern const base::Feature kTopOfStackAdTagging;
 }
 
 // Tracker for tagging resources as ads based on the call stack scripts.
@@ -134,10 +133,6 @@ class CORE_EXPORT AdTracker : public GarbageCollected<AdTracker> {
   // callstack to run (e.g., registered callbacks).
   const bool async_stack_enabled_;
 
-  // True if the TopOfStack experiment is running, which forces the AdTracker to
-  // ignore the bottom of stack frames when looking for ad script.
-  const bool top_of_stack_only_;
-
   DISALLOW_COPY_AND_ASSIGN(AdTracker);
 };
 

third_party/blink/renderer/core/frame/ad_tracker_test.cc

@@ -262,36 +262,6 @@ TEST_F(AdTrackerTest, TopScriptTaggedAsAdResource) {
       AdTracker::StackType::kBottomOnly));
 }
 
-TEST_F(AdTrackerTest, TopOfStackOnly_NoAdsOnTop) {
-  base::test::ScopedFeatureList feature_list;
-  feature_list.InitAndEnableFeature(features::kTopOfStackAdTagging);
-  CreateAdTracker();
-
-  String ad_script_url("https://example.com/bar.js");
-  AppendToKnownAdScripts(ad_script_url);
-
-  WillExecuteScript(ad_script_url);
-  WillExecuteScript("https://example.com/foo.js");
-  ad_tracker_->SetScriptAtTopOfStack("https://www.example.com/baz.js");
-
-  EXPECT_FALSE(AnyExecutingScriptsTaggedAsAdResource());
-}
-
-TEST_F(AdTrackerTest, TopOfStackOnly_AdsOnTop) {
-  base::test::ScopedFeatureList feature_list;
-  feature_list.InitAndEnableFeature(features::kTopOfStackAdTagging);
-  CreateAdTracker();
-
-  String ad_script_url("https://example.com/bar.js");
-  AppendToKnownAdScripts(ad_script_url);
-
-  WillExecuteScript(ad_script_url);
-  WillExecuteScript("https://example.com/foo.js");
-  ad_tracker_->SetScriptAtTopOfStack(ad_script_url);
-
-  EXPECT_TRUE(AnyExecutingScriptsTaggedAsAdResource());
-}
-
 // Tests that if neither script in the stack is an ad,
 // AnyExecutingScriptsTaggedAsAdResource should return false.
 TEST_F(AdTrackerTest, AnyExecutingScriptsTaggedAsAdResource_False) {