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

ash/system/chromeos/brightness/tray_brightness_unittest.cc

 // 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.
 
 #include "ash/system/chromeos/brightness/tray_brightness.h"
 
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/system_tray_item.h"
 #include "ash/test/ash_test_base.h"
 #include "ash/test/status_area_widget_test_helper.h"
 #include "ash/wm/maximize_mode/maximize_mode_controller.h"
 #include "ui/views/view.h"
 
 namespace ash {
 
 class TrayBrightnessTest : public test::AshTestBase {
  public:
   TrayBrightnessTest() {}
-  virtual ~TrayBrightnessTest() {}
+  ~TrayBrightnessTest() override {}
 
  protected:
   views::View* CreateDefaultView() {
     TrayBrightness tray(NULL);
     return tray.CreateDefaultView(
         StatusAreaWidgetTestHelper::GetUserLoginStatus());
   }
 
   views::View* CreateDetailedView() {
     TrayBrightness tray(NULL);
@@ skipping 61 matching lines @@
   Shell::GetInstance()->maximize_mode_controller()->
       EnableMaximizeModeWindowManager(true);
   EXPECT_TRUE(tray->visible());
   Shell::GetInstance()->maximize_mode_controller()->
       EnableMaximizeModeWindowManager(false);
   EXPECT_TRUE(tray->visible());
 }
 
 }  // namespace ash