C++11 override style change for athena

athena/screen/screen_accelerator_handler.h

 // Copyright 2014 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 ATHENA_SCREEN_SCREEN_ACCELERATOR_HANDLER_H_
 #define ATHENA_SCREEN_SCREEN_ACCELERATOR_HANDLER_H_
 
 #include "athena/input/public/accelerator_manager.h"
 
 #include "base/macros.h"
 
 namespace aura {
 class Window;
 }
 
 namespace athena {
 
 // Handles screen related accelerators.
 class ScreenAcceleratorHandler : public AcceleratorHandler {
  public:
   explicit ScreenAcceleratorHandler(aura::Window* root_window);
 
  private:
-  virtual ~ScreenAcceleratorHandler();
+  ~ScreenAcceleratorHandler() override;
 
   // AcceleratorHandler:
   virtual bool IsCommandEnabled(int command_id) const override;
   virtual bool OnAcceleratorFired(int command_id,
                                   const ui::Accelerator& accelerator) override;
 
   aura::Window* root_window_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenAcceleratorHandler);
 };
 
 }  // namespace athena
 
 #endif  // ATHENA_SCREEN_SCREEN_ACCELERATOR_HANDLER_H_