Prevent overlay scrollbars expand or hover together

cc/input/single_scrollbar_animation_controller_thinning.h

Index: cc/input/single_scrollbar_animation_controller_thinning.h
diff --git a/cc/input/scrollbar_animation_controller_thinning.h b/cc/input/single_scrollbar_animation_controller_thinning.h
similarity index 75%
copy from cc/input/scrollbar_animation_controller_thinning.h
copy to cc/input/single_scrollbar_animation_controller_thinning.h
index 0b393088b89c209f5771c617781c4bce7a264f89..b62b215d6e08675ba3cace8a5ca5128eca9e49f9 100644
--- a/cc/input/scrollbar_animation_controller_thinning.h
+++ b/cc/input/single_scrollbar_animation_controller_thinning.h
@@ -2,8 +2,8 @@
 // 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_THINNING_H_
-#define CC_INPUT_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_
+#ifndef CC_INPUT_SINGLE_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_
+#define CC_INPUT_SINGLE_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_
 
 #include <memory>
 
@@ -13,24 +13,25 @@
 
 namespace cc {
 
-// Scrollbar animation that partially fades and thins after an idle delay,
-// and reacts to mouse movements.
-class CC_EXPORT ScrollbarAnimationControllerThinning
+// ScrollbarAnimationControllerThinning for one scrollbar
+class CC_EXPORT SingleScrollbarAnimationControllerThinning
     : public ScrollbarAnimationController {
  public:
-  static std::unique_ptr<ScrollbarAnimationControllerThinning> Create(
+  static std::unique_ptr<SingleScrollbarAnimationControllerThinning> Create(
       int scroll_layer_id,
+      ScrollbarOrientation orientation,
       ScrollbarAnimationControllerClient* client,
       base::TimeDelta delay_before_starting,
       base::TimeDelta resize_delay_before_starting,
       base::TimeDelta fade_duration,
       base::TimeDelta thinning_duration);
 
-  ~ScrollbarAnimationControllerThinning() override;
+  ~SingleScrollbarAnimationControllerThinning() override {}
 
   void set_mouse_move_distance_for_test(float distance) {
     mouse_move_distance_to_trigger_animation_ = distance;
   }
+  ScrollbarOrientation orientation() const { return orientation_; }
   bool mouse_is_over_scrollbar() const { return mouse_is_over_scrollbar_; }
   bool mouse_is_near_scrollbar() const { return mouse_is_near_scrollbar_; }
 
@@ -39,21 +40,21 @@ class CC_EXPORT ScrollbarAnimationControllerThinning
   void DidMouseDown() override;
   void DidMouseUp() override;
   void DidMouseLeave() override;
-  void DidMouseMoveNear(float distance) override;
   bool ScrollbarsHidden() const override;
+  void RunAnimationFrame(float progress) override;
+  const base::TimeDelta& Duration() override;
+  void DidMouseMoveNear(ScrollbarOrientation, float) override;
 
  protected:
-  ScrollbarAnimationControllerThinning(
+  SingleScrollbarAnimationControllerThinning(
       int scroll_layer_id,
+      ScrollbarOrientation orientation,
       ScrollbarAnimationControllerClient* client,
       base::TimeDelta delay_before_starting,
       base::TimeDelta resize_delay_before_starting,
       base::TimeDelta fade_duration,
       base::TimeDelta thinning_duration);
 
-  void RunAnimationFrame(float progress) override;
-  const base::TimeDelta& Duration() override;
-
  private:
   // Describes whether the current animation should INCREASE (thicken)
   // a bar or DECREASE it (thin).
@@ -70,6 +71,7 @@ class CC_EXPORT ScrollbarAnimationControllerThinning
 
   void SetCurrentAnimatingProperty(AnimatingProperty property);
 
+  ScrollbarOrientation orientation_;
   float opacity_;
   bool captured_;
   bool mouse_is_over_scrollbar_;
@@ -84,9 +86,9 @@ class CC_EXPORT ScrollbarAnimationControllerThinning
 
   AnimatingProperty current_animating_property_;
 
-  DISALLOW_COPY_AND_ASSIGN(ScrollbarAnimationControllerThinning);
+  DISALLOW_COPY_AND_ASSIGN(SingleScrollbarAnimationControllerThinning);
 };
 
 }  // namespace cc
 
-#endif  // CC_INPUT_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_
+#endif  // CC_INPUT_SINGLE_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_