Implement fade-out animation for Aura overlay scrollbars (CC only).

cc/input/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_INPUT_SCROLLBAR_ANIMATION_CONTROLLER_H_
 #define CC_INPUT_SCROLLBAR_ANIMATION_CONTROLLER_H_
 
 #include "base/cancelable_callback.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
@@ skipping 43 matching lines @@
                                base::TimeDelta duration);
 
   virtual void RunAnimationFrame(float progress) = 0;
 
   void StartAnimation();
   void StopAnimation();
   ScrollbarSet Scrollbars() const;
 
   ScrollbarAnimationControllerClient* client_;
 
+  void PostDelayedAnimationTask(bool on_resize);
+
+  base::TimeDelta duration_;

[aelias_OOO_until_Jul13, 2016/10/20 23:40:51]

Could you replace this with a pure virtual getter, and move this state to
ScrollbarAnimationControllerLinearFade?

[bokan, 2016/10/21 00:32:30]

You mean move the state into both descendant classes right? Done.

+
  private:
   // Returns how far through the animation we are as a progress value from
   // 0 to 1.
   float AnimationProgressAtTime(base::TimeTicks now);
 
-  void PostDelayedAnimationTask(bool on_resize);
-
   base::TimeTicks last_awaken_time_;
   base::TimeDelta delay_before_starting_;
   base::TimeDelta resize_delay_before_starting_;
-  base::TimeDelta duration_;
 
   bool is_animating_;
 
   int scroll_layer_id_;
   bool currently_scrolling_;
   bool scroll_gesture_has_scrolled_;
   base::CancelableClosure delayed_scrollbar_fade_;
 
   base::WeakPtrFactory<ScrollbarAnimationController> weak_factory_;
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_SCROLLBAR_ANIMATION_CONTROLLER_H_