Standardize usage of virtual/override/final in cc/

cc/animation/scrollbar_animation_controller_linear_fade.h

 // Copyright 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.
 
 #ifndef CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_LINEAR_FADE_H_
 #define CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_LINEAR_FADE_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/animation/scrollbar_animation_controller.h"
 #include "cc/base/cc_export.h"
 
 namespace cc {
 class LayerImpl;
 
 class CC_EXPORT ScrollbarAnimationControllerLinearFade
     : public ScrollbarAnimationController {
  public:
   static scoped_ptr<ScrollbarAnimationControllerLinearFade> Create(
       LayerImpl* scroll_layer,
       ScrollbarAnimationControllerClient* client,
       base::TimeDelta delay_before_starting,
       base::TimeDelta resize_delay_before_starting,
       base::TimeDelta duration);
 
-  virtual ~ScrollbarAnimationControllerLinearFade();
+  ~ScrollbarAnimationControllerLinearFade() override;
 
-  virtual void DidScrollUpdate(bool on_resize) override;
+  void DidScrollUpdate(bool on_resize) override;
 
  protected:
   ScrollbarAnimationControllerLinearFade(
       LayerImpl* scroll_layer,
       ScrollbarAnimationControllerClient* client,
       base::TimeDelta delay_before_starting,
       base::TimeDelta resize_delay_before_starting,
       base::TimeDelta duration);
 
-  virtual void RunAnimationFrame(float progress) override;
+  void RunAnimationFrame(float progress) override;
 
  private:
   float OpacityAtTime(base::TimeTicks now) const;
   void ApplyOpacityToScrollbars(float opacity);
 
   LayerImpl* scroll_layer_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollbarAnimationControllerLinearFade);
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_LINEAR_FADE_H_