Feed ScrollableArea::showOverlayScrollbars into ScrollbarAnimationController.

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 67 matching lines @@
   void DidResize();
 
   void DidScrollBegin();
   void DidScrollEnd();
 
   void DidMouseDown();
   void DidMouseUp();
   void DidMouseLeave();
   void DidMouseMoveNear(ScrollbarOrientation, float);
 
+  // Called when Blink wants to show the scrollbars (via
+  // ScrollableArea::showOverlayScrollbars).
+  void DidRequestShowFromMainThread();
+
   bool MouseIsOverScrollbar(ScrollbarOrientation orientation) const;
   bool MouseIsNearScrollbar(ScrollbarOrientation orientation) const;
   bool MouseIsNearAnyScrollbar() const;
 
   static constexpr float kMouseMoveDistanceToTriggerShow = 30.0f;
 
  private:
   ScrollbarAnimationController(int scroll_layer_id,
                                ScrollbarAnimationControllerClient* client,
                                base::TimeDelta fade_out_delay,
@@ skipping 62 matching lines @@
       vertical_controller_;
   std::unique_ptr<SingleScrollbarAnimationControllerThinning>
       horizontal_controller_;
 
   base::WeakPtrFactory<ScrollbarAnimationController> weak_factory_;
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_SCROLLBAR_ANIMATION_CONTROLLER_H_