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

ash/system/chromeos/settings/tray_settings.h

 // Copyright (c) 2012 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_SYSTEM_CHROMEOS_SETTINGS_TRAY_SETTINGS_H_
 #define ASH_SYSTEM_CHROMEOS_SETTINGS_TRAY_SETTINGS_H_
 
 #include "ash/system/tray/system_tray_item.h"
 
 namespace ash {
 namespace tray {
 class SettingsDefaultView;
 }
 
 class TraySettings : public SystemTrayItem {
  public:
   explicit TraySettings(SystemTray* system_tray);
-  virtual ~TraySettings();
+  ~TraySettings() override;
 
  private:
   // Overridden from SystemTrayItem
-  virtual views::View* CreateTrayView(user::LoginStatus status) override;
-  virtual views::View* CreateDefaultView(user::LoginStatus status) override;
-  virtual views::View* CreateDetailedView(user::LoginStatus status) override;
-  virtual void DestroyTrayView() override;
-  virtual void DestroyDefaultView() override;
-  virtual void DestroyDetailedView() override;
-  virtual void UpdateAfterLoginStatusChange(user::LoginStatus status) override;
+  views::View* CreateTrayView(user::LoginStatus status) override;
+  views::View* CreateDefaultView(user::LoginStatus status) override;
+  views::View* CreateDetailedView(user::LoginStatus status) override;
+  void DestroyTrayView() override;
+  void DestroyDefaultView() override;
+  void DestroyDetailedView() override;
+  void UpdateAfterLoginStatusChange(user::LoginStatus status) override;
 
   tray::SettingsDefaultView* default_view_;
 
   DISALLOW_COPY_AND_ASSIGN(TraySettings);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_SETTINGS_TRAY_SETTINGS_H_