Update {virtual,override,final} to follow C++11 style in ash.

ash/display/display_change_observer_chromeos.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 ASH_DISPLAY_DISPLAY_CHANGE_OBSERVER_CHROMEOS_H_
 #define ASH_DISPLAY_DISPLAY_CHANGE_OBSERVER_CHROMEOS_H_
 
 #include <vector>
 
 #include "ash/ash_export.h"
@@ skipping 17 matching lines @@
   // Returns the mode list for internal display.
   ASH_EXPORT static std::vector<DisplayMode> GetInternalDisplayModeList(
       const DisplayInfo& display_info,
       const ui::DisplayConfigurator::DisplayState& output);
 
   // Returns the resolution list.
   ASH_EXPORT static std::vector<DisplayMode> GetExternalDisplayModeList(
       const ui::DisplayConfigurator::DisplayState& output);
 
   DisplayChangeObserver();
-  virtual ~DisplayChangeObserver();
+  ~DisplayChangeObserver() override;
 
   // ui::DisplayConfigurator::StateController overrides:
-  virtual ui::MultipleDisplayState GetStateForDisplayIds(
+  ui::MultipleDisplayState GetStateForDisplayIds(
       const std::vector<int64>& outputs) const override;
-  virtual bool GetResolutionForDisplayId(int64 display_id,
-                                         gfx::Size* size) const override;
+  bool GetResolutionForDisplayId(int64 display_id,
+                                 gfx::Size* size) const override;
 
   // Overriden from ui::DisplayConfigurator::Observer:
-  virtual void OnDisplayModeChanged(
+  void OnDisplayModeChanged(
       const ui::DisplayConfigurator::DisplayStateList& outputs) override;
 
   // Overriden from ui::InputDeviceEventObserver:
-  virtual void OnTouchscreenDeviceConfigurationChanged() override;
-  virtual void OnKeyboardDeviceConfigurationChanged() override;
+  void OnTouchscreenDeviceConfigurationChanged() override;
+  void OnKeyboardDeviceConfigurationChanged() override;
 
   // Overriden from ShellObserver:
-  virtual void OnAppTerminating() override;
+  void OnAppTerminating() override;
 
   // Exposed for testing.
   ASH_EXPORT static float FindDeviceScaleFactor(float dpi);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DisplayChangeObserver);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_DISPLAY_CHANGE_OBSERVER_CHROMEOS_H_