Add OVERRIDE to chrome/browser/chromeos/.

chrome/browser/chromeos/brightness_observer.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 CHROME_BROWSER_CHROMEOS_BRIGHTNESS_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_BRIGHTNESS_OBSERVER_H_
 #pragma once
 
 #include "base/basictypes.h"
+#include "base/compiler_specific.h"
 #include "chrome/browser/chromeos/dbus/power_manager_client.h"
 
 namespace chromeos {
 
 // This observer displays a bubble at the bottom of the screen showing the
 // current brightness level whenever the user changes it.
 class BrightnessObserver : public PowerManagerClient::Observer {
  public:
   BrightnessObserver() {}
   virtual ~BrightnessObserver() {}
 
  private:
   // PowerManagerClient::Observer implementation.
-  virtual void BrightnessChanged(int level, bool user_initiated);
+  virtual void BrightnessChanged(int level, bool user_initiated) OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(BrightnessObserver);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_BRIGHTNESS_OBSERVER_H_