Update from https://crrev.com/318214

cc/animation/scrollbar_animation_controller.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_H_
 #define CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_H_
 
 #include "base/cancelable_callback.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "cc/base/cc_export.h"
+#include "cc/layers/layer_impl.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 
 namespace cc {
 
+class ScrollbarAnimationController;
+
 class CC_EXPORT ScrollbarAnimationControllerClient {
  public:
+  virtual void StartAnimatingScrollbarAnimationController(
+      ScrollbarAnimationController* controller) = 0;
+  virtual void StopAnimatingScrollbarAnimationController(
+      ScrollbarAnimationController* controller) = 0;
+  virtual void PostDelayedScrollbarAnimationTask(const base::Closure& task,
+                                                 base::TimeDelta delay) = 0;
+  virtual void SetNeedsRedrawForScrollbarAnimation() = 0;
+
+ protected:
   virtual ~ScrollbarAnimationControllerClient() {}
-
-  virtual void PostDelayedScrollbarFade(const base::Closure& start_fade,
-                                        base::TimeDelta delay) = 0;
-  virtual void SetNeedsScrollbarAnimationFrame() = 0;
 };
 
 // This abstract class represents the compositor-side analogy of
 // ScrollbarAnimator.  Individual platforms should subclass it to provide
 // specialized implementation.
 class CC_EXPORT ScrollbarAnimationController {
  public:
   virtual ~ScrollbarAnimationController();
 
   void Animate(base::TimeTicks now);
 
   virtual void DidScrollBegin();
   virtual void DidScrollUpdate(bool on_resize);
   virtual void DidScrollEnd();
   virtual void DidMouseMoveOffScrollbar() {}
   virtual void DidMouseMoveNear(float distance) {}
 
  protected:
-  ScrollbarAnimationController(ScrollbarAnimationControllerClient* client,
+  ScrollbarAnimationController(LayerImpl* scroll_layer,
+                               ScrollbarAnimationControllerClient* client,
                                base::TimeDelta delay_before_starting,
                                base::TimeDelta resize_delay_before_starting,
                                base::TimeDelta duration);
 
   virtual void RunAnimationFrame(float progress) = 0;
 
   void StartAnimation();
   void StopAnimation();
 
+  LayerImpl* scroll_layer_;
+  ScrollbarAnimationControllerClient* client_;
+
  private:
   // Returns how far through the animation we are as a progress value from
   // 0 to 1.
   float AnimationProgressAtTime(base::TimeTicks now);
 
-  void PostDelayedFade(bool on_resize);
+  void PostDelayedAnimationTask(bool on_resize);
 
-  ScrollbarAnimationControllerClient* client_;
   base::TimeTicks last_awaken_time_;
   base::TimeDelta delay_before_starting_;
   base::TimeDelta resize_delay_before_starting_;
   base::TimeDelta duration_;
+
   bool is_animating_;
 
   bool currently_scrolling_;
   bool scroll_gesture_has_scrolled_;
   base::CancelableClosure delayed_scrollbar_fade_;
 
   base::WeakPtrFactory<ScrollbarAnimationController> weak_factory_;
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_H_