Move setup of base::test::ScopedFeatureList earlier, to avoid data race.

content/browser/top_document_isolation_browsertest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/test/scoped_feature_list.h"
 #include "content/browser/frame_host/frame_tree_node.h"
 #include "content/browser/web_contents/web_contents_impl.h"
@@ skipping 13 matching lines @@
 
 class TopDocumentIsolationTest : public ContentBrowserTest {
  public:
   TopDocumentIsolationTest() {}
 
  protected:
   std::string DepictFrameTree(FrameTreeNode* node) {
     return visualizer_.DepictFrameTree(node);
   }
 
+  void SetUp() override {
+    scoped_feature_list_.InitAndEnableFeature(features::kTopDocumentIsolation);
+    ContentBrowserTest::SetUp();
+  }
+
   void SetUpOnMainThread() override {
-    scoped_feature_list_.InitAndEnableFeature(features::kTopDocumentIsolation);
     host_resolver()->AddRule("*", "127.0.0.1");
     SetupCrossSiteRedirector(embedded_test_server());
     ASSERT_TRUE(embedded_test_server()->Start());
   }
 
   FrameTreeNode* root() {
     return static_cast<WebContentsImpl*>(shell()->web_contents())
         ->GetFrameTree()
         ->root();
   }
@@ skipping 557 matching lines @@
       "      C = http://adnetwork.com/",
       DepictFrameTree(root()));
   EXPECT_EQ(
       " Site C ------------ proxies for B\n"
       "Where B = default subframe process\n"
       "      C = http://adnetwork.com/",
       DepictFrameTree(popup_root));
 }
 
 }  // namespace content