Revert of Use FrameIsAd to decide whether to isolate a frame in TopDocumentIsolation mode.

content/browser/top_document_isolation_browsertest.cc

Index: content/browser/top_document_isolation_browsertest.cc
diff --git a/content/browser/top_document_isolation_browsertest.cc b/content/browser/top_document_isolation_browsertest.cc
index 5d5c4d5161741ae3ef7c8a62cb581952df0b94e9..cb57f0681e8bcb2f326a62c29c2ab0f1e8f3ae10 100644
--- a/content/browser/top_document_isolation_browsertest.cc
+++ b/content/browser/top_document_isolation_browsertest.cc
@@ -5,6 +5,7 @@
 #include <string>
 
 #include "base/command_line.h"
+#include "base/test/scoped_feature_list.h"
 #include "build/build_config.h"
 #include "content/browser/frame_host/frame_tree_node.h"
 #include "content/browser/web_contents/web_contents_impl.h"
@@ -31,9 +32,9 @@
     return visualizer_.DepictFrameTree(node);
   }
 
-  void SetUpCommandLine(base::CommandLine* command_line) override {
-    ContentBrowserTest::SetUpCommandLine(command_line);
-    content::EnableTopDocumentIsolationForTesting(command_line);
+  void SetUp() override {
+    scoped_feature_list_.InitAndEnableFeature(features::kTopDocumentIsolation);
+    ContentBrowserTest::SetUp();
   }
 
   void SetUpOnMainThread() override {
@@ -69,6 +70,7 @@
 
  private:
   FrameTreeVisualizer visualizer_;
+  base::test::ScopedFeatureList scoped_feature_list_;
 
   DISALLOW_COPY_AND_ASSIGN(TopDocumentIsolationTest);
 };