Standardize usage of virtual/override/final specifiers.

ash/system/date/date_default_view.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 ASH_SYSTEM_DATE_DATE_DEFAULT_VIEW_H_
 #define ASH_SYSTEM_DATE_DATE_DEFAULT_VIEW_H_
 
 #include "ash/ash_export.h"
 #include "ash/system/user/login_status.h"
 #include "base/macros.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/view.h"
 
 namespace ash {
 namespace tray {
 class DateView;
 }  // namespace tray
 
 class TrayPopupHeaderButton;
 
 class ASH_EXPORT DateDefaultView : public views::View,
                                    public views::ButtonListener {
  public:
   explicit DateDefaultView(ash::user::LoginStatus login);
 
-  virtual ~DateDefaultView();
+  ~DateDefaultView() override;
 
   views::View* GetHelpButtonView();
 
   tray::DateView* GetDateView();
   const tray::DateView* GetDateView() const;
 
  private:
   // Overridden from views::ButtonListener.
-  virtual void ButtonPressed(views::Button* sender,
-                             const ui::Event& event) override;
+  void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
   TrayPopupHeaderButton* help_;
   TrayPopupHeaderButton* shutdown_;
   TrayPopupHeaderButton* lock_;
   tray::DateView* date_view_;
 
   DISALLOW_COPY_AND_ASSIGN(DateDefaultView);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_DATE_DATE_DEFAULT_VIEW_H_