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

ash/system/chromeos/power/tray_power.cc

 // 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.
 
 #include "ash/system/chromeos/power/tray_power.h"
 
 #include "ash/accessibility_delegate.h"
 #include "ash/ash_switches.h"
 #include "ash/shell.h"
 #include "ash/system/chromeos/power/power_status_view.h"
@@ skipping 29 matching lines @@
 namespace ash {
 namespace tray {
 
 // This view is used only for the tray.
 class PowerTrayView : public views::ImageView {
  public:
   PowerTrayView() {
     UpdateImage();
   }
 
-  virtual ~PowerTrayView() {
-  }
+  ~PowerTrayView() override {}
 
   // Overriden from views::View.
-  virtual void GetAccessibleState(ui::AXViewState* state) override {
+  void GetAccessibleState(ui::AXViewState* state) override {
     state->name = accessible_name_;
     state->role = ui::AX_ROLE_BUTTON;
   }
 
   void UpdateStatus(bool battery_alert) {
     UpdateImage();
     SetVisible(PowerStatus::Get()->IsBatteryPresent());
 
     if (battery_alert) {
       accessible_name_ = PowerStatus::Get()->GetAccessibleNameString(true);
@@ skipping 237 matching lines @@
       }
       return false;
     case NOTIFICATION_CRITICAL:
       return false;
   }
   NOTREACHED();
   return false;
 }
 
 }  // namespace ash