Merge Compositor's ScrollbarAnimationControllers into single class

cc/input/single_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_INPUT_SINGLE_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_
 #define CC_INPUT_SINGLE_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "cc/base/cc_export.h"
 #include "cc/input/scrollbar.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/layers/scrollbar_layer_impl_base.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 
 namespace cc {
 
 class ScrollbarAnimationControllerClient;
 
 // ScrollbarAnimationControllerThinning for one scrollbar
 class CC_EXPORT SingleScrollbarAnimationControllerThinning {
  public:
+  static constexpr float kIdleThicknessScale = 0.4f;
+  static constexpr float kDefaultMouseMoveDistanceToTriggerAnimation = 25.f;
+
   static std::unique_ptr<SingleScrollbarAnimationControllerThinning> Create(
       int scroll_layer_id,
       ScrollbarOrientation orientation,
       ScrollbarAnimationControllerClient* client,
       base::TimeDelta thinning_duration);
 
   ~SingleScrollbarAnimationControllerThinning() {}
 
-  void set_mouse_move_distance_for_test(float distance) {
-    mouse_move_distance_to_trigger_animation_ = distance;
-  }
   bool mouse_is_over_scrollbar() const { return mouse_is_over_scrollbar_; }
   bool mouse_is_near_scrollbar() const { return mouse_is_near_scrollbar_; }
   bool captured() const { return captured_; }
 
   bool Animate(base::TimeTicks now);
   void StartAnimation();
   void StopAnimation();
 
   void UpdateThumbThicknessScale();
 
@@ skipping 31 matching lines @@
   bool is_animating_;
 
   int scroll_layer_id_;
 
   ScrollbarOrientation orientation_;
   bool captured_;
   bool mouse_is_over_scrollbar_;
   bool mouse_is_near_scrollbar_;
   // Are we narrowing or thickening the bars.
   AnimationChange thickness_change_;
-  // How close should the mouse be to the scrollbar before we thicken it.
-  float mouse_move_distance_to_trigger_animation_;
 
   base::TimeDelta thinning_duration_;
 
   DISALLOW_COPY_AND_ASSIGN(SingleScrollbarAnimationControllerThinning);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_SINGLE_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_