Feed ScrollableArea::showOverlayScrollbars into ScrollbarAnimationController.

third_party/WebKit/Source/platform/scroll/ScrollableArea.h

 /*
  * Copyright (C) 2008, 2011 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 286 matching lines @@
   virtual GraphicsLayer* layerForContainer() const;
   virtual GraphicsLayer* layerForScrolling() const { return 0; }
   virtual GraphicsLayer* layerForHorizontalScrollbar() const { return 0; }
   virtual GraphicsLayer* layerForVerticalScrollbar() const { return 0; }
   virtual GraphicsLayer* layerForScrollCorner() const { return 0; }
   bool hasLayerForHorizontalScrollbar() const;
   bool hasLayerForVerticalScrollbar() const;
   bool hasLayerForScrollCorner() const;
 
   void layerForScrollingDidChange(CompositorAnimationTimeline*);
+  bool needsShowScrollbarLayers() const { return m_needsShowScrollbarLayers; }
+  void didShowScrollbarLayers() { m_needsShowScrollbarLayers = false; }
 
   void cancelScrollAnimation();
   virtual void cancelProgrammaticScrollAnimation();
 
   virtual ~ScrollableArea();
 
   // Called when any of horizontal scrollbar, vertical scrollbar and scroll
   // corner is setNeedsPaintInvalidation.
   virtual void scrollControlWasSetNeedsPaintInvalidation() = 0;
 
@@ skipping 122 matching lines @@
 
   unsigned m_scrollOriginChanged : 1;
 
   unsigned m_horizontalScrollbarNeedsPaintInvalidation : 1;
   unsigned m_verticalScrollbarNeedsPaintInvalidation : 1;
   unsigned m_scrollCornerNeedsPaintInvalidation : 1;
   unsigned m_scrollbarsHidden : 1;
   unsigned m_scrollbarCaptured : 1;
   unsigned m_mouseOverScrollbar : 1;
 
+  // Indicates that the next compositing update needs to call
+  // WebLayer::showScrollbars on our scroll layer. Ignored if not composited.
+  unsigned m_needsShowScrollbarLayers : 1;
+
   // There are 6 possible combinations of writing mode and direction. Scroll
   // origin will be non-zero in the x or y axis if there is any reversed
   // direction or writing-mode. The combinations are:
   // writing-mode / direction     scrollOrigin.x() set    scrollOrigin.y() set
   // horizontal-tb / ltr          NO                      NO
   // horizontal-tb / rtl          YES                     NO
   // vertical-lr / ltr            NO                      NO
   // vertical-lr / rtl            NO                      YES
   // vertical-rl / ltr            YES                     NO
   // vertical-rl / rtl            YES                     YES
   IntPoint m_scrollOrigin;
 };
 
 }  // namespace blink
 
 #endif  // ScrollableArea_h