Added a master switch to enable/disable gpu acceleration.

chrome/browser/tab_contents/render_view_host_delegate_helper.h

 // Copyright (c) 2010 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 CHROME_BROWSER_TAB_CONTENTS_RENDER_VIEW_HOST_DELEGATE_HELPER_H_
 #define CHROME_BROWSER_TAB_CONTENTS_RENDER_VIEW_HOST_DELEGATE_HELPER_H_
 #pragma once
 
 #include <map>
 
@@ skipping 86 matching lines @@
 // RenderViewHostDelegate methods.
 class RenderViewHostDelegateHelper {
  public:
   static WebPreferences GetWebkitPrefs(Profile* profile, bool is_dom_ui);
 
   static void UpdateInspectorSetting(Profile* profile,
                                      const std::string& key,
                                      const std::string& value);
   static void ClearInspectorSettings(Profile* profile);
 
+  static bool gpu_enabled() { return gpu_enabled_; }
+  static void set_gpu_enabled(bool enabled) { gpu_enabled_ = enabled; }
+
  private:
   RenderViewHostDelegateHelper();
 
+  // Master switch for enabling/disabling GPU acceleration for the current
+  // browser session. It does not change the acceleration settings for
+  // existing tabs, just the future ones.
+  static bool gpu_enabled_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderViewHostDelegateHelper);
 };
 
 #endif  // CHROME_BROWSER_TAB_CONTENTS_RENDER_VIEW_HOST_DELEGATE_HELPER_H_