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

ash/system/chromeos/enterprise/tray_enterprise.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_ENTERPRISE_TRAY_ENTERPRISE_H
 #define ASH_SYSTEM_CHROMEOS_ENTERPRISE_TRAY_ENTERPRISE_H
 
 #include "ash/system/chromeos/enterprise/enterprise_domain_observer.h"
 #include "ash/system/tray/system_tray_item.h"
 #include "ash/system/tray/view_click_listener.h"
 
 namespace views {
 class View;
 }
 
 namespace ash {
 class LabelTrayView;
 class SystemTray;
 
 class TrayEnterprise : public SystemTrayItem,
                        public ViewClickListener,
                        public EnterpriseDomainObserver {
  public:
   explicit TrayEnterprise(SystemTray* system_tray);
-  virtual ~TrayEnterprise();
+  ~TrayEnterprise() override;
 
   // If message is not empty updates content of default view, otherwise hides
   // tray items.
   void UpdateEnterpriseMessage();
 
   // Overridden from SystemTrayItem.
-  virtual views::View* CreateDefaultView(user::LoginStatus status) override;
-  virtual void DestroyDefaultView() override;
+  views::View* CreateDefaultView(user::LoginStatus status) override;
+  void DestroyDefaultView() override;
 
   // Overridden from EnterpriseDomainObserver.
-  virtual void OnEnterpriseDomainChanged() override;
+  void OnEnterpriseDomainChanged() override;
 
   // Overridden from ViewClickListener.
-  virtual void OnViewClicked(views::View* sender) override;
+  void OnViewClicked(views::View* sender) override;
 
  private:
   LabelTrayView* tray_view_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayEnterprise);
 };
 
 } // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_ENTERPRISE_TRAY_ENTERPRISE_H