Standardize usage of virtual/override/final in chrome/renderer/

chrome/renderer/extensions/extension_frame_helper.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 CHROME_RENDERER_EXTENSIONS_EXTENSION_FRAME_HELPER_H_
 #define CHROME_RENDERER_EXTENSIONS_EXTENSION_FRAME_HELPER_H_
 
 #include "content/public/common/console_message_level.h"
 #include "content/public/renderer/render_frame_observer.h"
 #include "content/public/renderer/render_frame_observer_tracker.h"
 
 namespace extensions {
 
 class Dispatcher;
 
 // RenderFrame-level plumbing for extension features.
 class ExtensionFrameHelper
     : public content::RenderFrameObserver,
       public content::RenderFrameObserverTracker<ExtensionFrameHelper> {
  public:
   ExtensionFrameHelper(content::RenderFrame* render_frame,
                        Dispatcher* extension_dispatcher);
-  virtual ~ExtensionFrameHelper();
+  ~ExtensionFrameHelper() override;
 
  private:
   // RenderFrameObserver implementation.
-  virtual void WillReleaseScriptContext(v8::Handle<v8::Context>,
-                                        int world_id) override;
-  virtual bool OnMessageReceived(const IPC::Message& message) override;
+  void WillReleaseScriptContext(v8::Handle<v8::Context>, int world_id) override;
+  bool OnMessageReceived(const IPC::Message& message) override;
 
   // IPC handlers.
   void OnAddMessageToConsole(content::ConsoleMessageLevel level,
                              const std::string& message);
 
   Dispatcher* extension_dispatcher_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionFrameHelper);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_RENDERER_EXTENSIONS_EXTENSION_FRAME_HELPER_H_