Standardize usage of virtual/override/final specifiers.

ash/system/tray/system_tray_bubble.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/tray/system_tray_bubble.h"
 
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/system_tray_item.h"
@@ skipping 28 matching lines @@
 const int kSwipeDelayMS = 150;
 
 // Implicit animation observer that deletes itself and the layer at the end of
 // the animation.
 class AnimationObserverDeleteLayer : public ui::ImplicitAnimationObserver {
  public:
   explicit AnimationObserverDeleteLayer(ui::Layer* layer)
       : layer_(layer) {
   }
 
-  virtual ~AnimationObserverDeleteLayer() {
-  }
+  ~AnimationObserverDeleteLayer() override {}
 
-  virtual void OnImplicitAnimationsCompleted() override {
+  void OnImplicitAnimationsCompleted() override {
     base::MessageLoopForUI::current()->DeleteSoon(FROM_HERE, this);
   }
 
  private:
   scoped_ptr<ui::Layer> layer_;
 
   DISALLOW_COPY_AND_ASSIGN(AnimationObserverDeleteLayer);
 };
 
 }  // namespace
@@ skipping 254 matching lines @@
     // 2 items, which are the bottom header row and the one just above it.
     bubble_view_->AddChildView(new TrayPopupItemContainer(
         item_views[i], is_default_bubble,
         is_default_bubble && (i < item_views.size() - 2)));
   }
   if (focus_view)
     focus_view->RequestFocus();
 }
 
 }  // namespace ash