Standardize usage of virtual/override/final specifiers.

ui/views/examples/message_box_example.h

Index: ui/views/examples/message_box_example.h
diff --git a/ui/views/examples/message_box_example.h b/ui/views/examples/message_box_example.h
index fe3ba6703e15f37d2edd226aeb9e93b3c81d0e42..2bed43b047c44c6064b7b4da3f4e6c70ebbcb1d0 100644
--- a/ui/views/examples/message_box_example.h
+++ b/ui/views/examples/message_box_example.h
@@ -21,14 +21,14 @@ class VIEWS_EXAMPLES_EXPORT MessageBoxExample : public ExampleBase,
                                                 public ButtonListener {
  public:
   MessageBoxExample();
-  virtual ~MessageBoxExample();
+  ~MessageBoxExample() 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;
 
   // The MessageBoxView to be tested.
   MessageBoxView* message_box_view_;