Standardize usage of virtual/override/final specifiers.

ui/views/controls/scrollbar/base_scroll_bar_button.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_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_BUTTON_H_
 #define UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_BUTTON_H_
 
 #include "ui/views/controls/button/custom_button.h"
 
 #include "ui/views/repeat_controller.h"
 
 #if defined(OS_LINUX)
 #include "ui/gfx/screen.h"
 #endif
 
 namespace views {
 
 ///////////////////////////////////////////////////////////////////////////////
 //
 // ScrollBarButton
 //
 //  A button that activates on mouse pressed rather than released, and that
 //  continues to fire the clicked action as the mouse button remains pressed
 //  down on the button.
 //
 ///////////////////////////////////////////////////////////////////////////////
 class VIEWS_EXPORT BaseScrollBarButton : public CustomButton {
  public:
   explicit BaseScrollBarButton(ButtonListener* listener);
-  virtual ~BaseScrollBarButton();
+  ~BaseScrollBarButton() override;
 
  protected:
-  virtual bool OnMousePressed(const ui::MouseEvent& event) override;
-  virtual void OnMouseReleased(const ui::MouseEvent& event) override;
-  virtual void OnMouseCaptureLost() override;
+  bool OnMousePressed(const ui::MouseEvent& event) override;
+  void OnMouseReleased(const ui::MouseEvent& event) override;
+  void OnMouseCaptureLost() override;
 
  private:
   void RepeaterNotifyClick();
 
   // The repeat controller that we use to repeatedly click the button when the
   // mouse button is down.
   RepeatController repeater_;
 
   DISALLOW_COPY_AND_ASSIGN(BaseScrollBarButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_BUTTON_H_