Standardize usage of virtual/override/final specifiers.

ui/views/examples/bubble_example.h

 // Copyright (c) 2011 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 UI_VIEWS_EXAMPLES_BUBBLE_EXAMPLE_H_
 #define UI_VIEWS_EXAMPLES_BUBBLE_EXAMPLE_H_
 
 #include "ui/views/controls/button/button.h"
 #include "ui/views/examples/example_base.h"
 
 namespace views {
 namespace examples {
 
 // A Bubble example.
 class VIEWS_EXAMPLES_EXPORT BubbleExample : public ExampleBase,
                                             public ButtonListener {
  public:
   BubbleExample();
-  virtual ~BubbleExample();
+  ~BubbleExample() override;
 
   // ExampleBase:
-  virtual void CreateExampleView(View* container) override;
+  void CreateExampleView(View* container) override;
 
  private:
   // ButtonListener:
-  virtual void ButtonPressed(Button* sender, const ui::Event& event) override;
+  void ButtonPressed(Button* sender, const ui::Event& event) override;
 
   Button* no_shadow_;
   Button* big_shadow_;
   Button* small_shadow_;
   Button* align_to_edge_;
   Button* persistent_;
 
   DISALLOW_COPY_AND_ASSIGN(BubbleExample);
 };
 
 }  // namespace examples
 }  // namespace views
 
 #endif  // UI_VIEWS_EXAMPLES_BUBBLE_EXAMPLE_H_