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

ash/system/chromeos/tray_display.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/tray_display.h"
 
 #include <vector>
 
 #include "ash/content/display/screen_orientation_controller_chromeos.h"
 #include "ash/display/display_controller.h"
@@ skipping 137 matching lines @@
         bundle.GetImageNamed(IDR_AURA_UBER_TRAY_DISPLAY).ToImageSkia());
     AddChildView(image_);
 
     label_ = new views::Label();
     label_->SetMultiLine(true);
     label_->SetHorizontalAlignment(gfx::ALIGN_LEFT);
     AddChildView(label_);
     Update();
   }
 
-  virtual ~DisplayView() {}
+  ~DisplayView() override {}
 
   void Update() {
     base::string16 message = GetTrayDisplayMessage(NULL);
     if (message.empty() && ShouldShowFirstDisplayInfo())
       message = GetDisplayInfoLine(GetDisplayManager()->first_display_id());
     SetVisible(!message.empty());
     label_->SetText(message);
     SetAccessibleName(message);
     Layout();
   }
@@ skipping 274 matching lines @@
 bool TrayDisplay::GetAccessibleStateForTesting(ui::AXViewState* state) {
   views::View* view = default_;
   if (view) {
     view->GetAccessibleState(state);
     return true;
   }
   return false;
 }
 
 }  // namespace ash