Reland #1: Fix re-usage of stale cached WebPreferences in RenderViewHost.

content/shell/browser/layout_test/blink_test_controller.h

 // Copyright 2013 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.
 
 #ifndef CONTENT_SHELL_BROWSER_LAYOUT_TEST_BLINK_TEST_CONTROLLER_H_
 #define CONTENT_SHELL_BROWSER_LAYOUT_TEST_BLINK_TEST_CONTROLLER_H_
 
 #include <map>
 #include <memory>
 #include <ostream>
@@ skipping 230 matching lines @@
 
   // True if the currently running test is a compositing test.
   bool is_compositing_test_;
 
   // Per test config.
   bool enable_pixel_dumping_;
   std::string expected_pixel_hash_;
   gfx::Size initial_size_;
   GURL test_url_;
 
+  // Stores the default test-adapted WebPreferences which is then used to fully
+  // reset the main window's preferences if and when it is reused.
+  WebPreferences default_prefs_;
+
   // True if the WebPreferences of newly created RenderViewHost should be
   // overridden with prefs_.
   bool should_override_prefs_;
   WebPreferences prefs_;
 
   NotificationRegistrar registrar_;
 
   const bool is_leak_detection_enabled_;
   bool crash_when_leak_found_;
 
@@ skipping 22 matching lines @@
   // waiting on the UI thread while layout tests are being ran.
   ScopedAllowWaitForAndroidLayoutTests reduced_restrictions_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(BlinkTestController);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_SHELL_BROWSER_LAYOUT_TEST_BLINK_TEST_CONTROLLER_H_