Add OVERRIDEs to RenderViewHostObserver subclasses that didn't already have them.

content/browser/debugger/devtools_handler.h

 // Copyright (c) 2011 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_BROWSER_DEBUGGER_DEVTOOLS_HANDLER_H_
 #define CONTENT_BROWSER_DEBUGGER_DEVTOOLS_HANDLER_H_
 #pragma once
 
 #include "content/browser/renderer_host/render_view_host_observer.h"
 
 class DevToolsClientHost;
 
 class DevToolsHandler : public RenderViewHostObserver {
  public:
   explicit DevToolsHandler(RenderViewHost* render_view_host);
   virtual ~DevToolsHandler();
 
   // RenderViewHostObserver overrides.
-  virtual bool OnMessageReceived(const IPC::Message& message);
+  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
  private:
   void OnForwardToAgent(const IPC::Message& message);
   void OnForwardToClient(const IPC::Message& message);
   void OnActivateWindow();
   void OnCloseWindow();
   void OnRequestDockWindow();
   void OnRequestUndockWindow();
   void OnSaveAs(const std::string& file_name,
                 const std::string& content);
   void OnRuntimePropertyChanged(const std::string& name,
                                 const std::string& value);
   void OnClearBrowserCache();
   void OnClearBrowserCookies();
 
   DevToolsClientHost* GetOwnerClientHost();
 
   DISALLOW_COPY_AND_ASSIGN(DevToolsHandler);
 };
 
 #endif  // CONTENT_BROWSER_DEBUGGER_DEVTOOLS_HANDLER_H_