Suppress scrollbar animation if the scroll gesture does not scroll

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,
       base::TimeDelta fadeout_delay,
       base::TimeDelta fadeout_length);
 
   virtual ~ScrollbarAnimationControllerLinearFade();
 
   // ScrollbarAnimationController overrides.
-  virtual bool IsScrollGestureInProgress() const OVERRIDE;
   virtual bool IsAnimating() const OVERRIDE;
   virtual base::TimeDelta DelayBeforeStart(base::TimeTicks now) const OVERRIDE;
 
   virtual bool Animate(base::TimeTicks now) OVERRIDE;
   virtual void DidScrollGestureBegin() OVERRIDE;
   virtual void DidScrollGestureEnd(base::TimeTicks now) OVERRIDE;
-  virtual void DidProgrammaticallyUpdateScroll(base::TimeTicks now) OVERRIDE;
+  virtual void DidScrollUpdate(base::TimeTicks now) OVERRIDE;
 
  protected:
   ScrollbarAnimationControllerLinearFade(LayerImpl* scroll_layer,
                                          base::TimeDelta fadeout_delay,
                                          base::TimeDelta fadeout_length);
 
  private:
   float OpacityAtTime(base::TimeTicks now);
 
   LayerImpl* scroll_layer_;
 
   base::TimeTicks last_awaken_time_;
   bool scroll_gesture_in_progress_;
+  bool scroll_gesture_has_scrolled_;
 
   base::TimeDelta fadeout_delay_;
   base::TimeDelta fadeout_length_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollbarAnimationControllerLinearFade);
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_LINEAR_FADE_H_