Update from https://crrev.com/318214

cc/animation/scrollbar_animation_controller_thinning.h

 // Copyright 2013 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_THINNING_H_
 #define CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/animation/scrollbar_animation_controller.h"
 #include "cc/base/cc_export.h"
@@ skipping 44 matching lines @@
     DECREASE
   };
   float OpacityAtAnimationProgress(float progress);
   float ThumbThicknessScaleAtAnimationProgress(float progress);
   float AdjustScale(float new_value,
                     float current_value,
                     AnimationChange animation_change);
   void ApplyOpacityAndThumbThicknessScale(float opacity,
                                           float thumb_thickness_scale);
 
-  LayerImpl* scroll_layer_;
-
   bool mouse_is_over_scrollbar_;
   bool mouse_is_near_scrollbar_;
   // Are we narrowing or thickening the bars.
   AnimationChange thickness_change_;
   // Are we darkening or lightening the bars.
   AnimationChange opacity_change_;
   // How close should the mouse be to the scrollbar before we thicken it.
   float mouse_move_distance_to_trigger_animation_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollbarAnimationControllerThinning);
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_