[RootLayerScrolls] Annotate non-fast-scroll regions to correct layer

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 23 matching lines @@
 #include "platform/heap/Handle.h"
 #include "platform/scroll/ScrollAnimatorBase.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "platform/scroll/Scrollbar.h"
 #include "wtf/MathExtras.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
+class ClientRectList;
 class CompositorAnimationHost;
 class CompositorAnimationTimeline;
 class GraphicsLayer;
 class HostWindow;
 class LayoutBox;
 class LayoutObject;
 class PaintLayer;
 class ProgrammaticScrollAnimator;
 struct ScrollAlignment;
 class ScrollAnchor;
@@ skipping 245 matching lines @@
   virtual GraphicsLayer* layerForScrollCorner() const { return 0; }
   bool hasLayerForHorizontalScrollbar() const;
   bool hasLayerForVerticalScrollbar() const;
   bool hasLayerForScrollCorner() const;
 
   void layerForScrollingDidChange(CompositorAnimationTimeline*);
 
   void cancelScrollAnimation();
   virtual void cancelProgrammaticScrollAnimation();
 
+  virtual ClientRectList* nonFastScrollableRects() const { return 0; }
+
   virtual ~ScrollableArea();
 
   // Called when any of horizontal scrollbar, vertical scrollbar and scroll
   // corner is setNeedsPaintInvalidation.
   virtual void scrollControlWasSetNeedsPaintInvalidation() = 0;
 
   // Returns the default scroll style this area should scroll with when not
   // explicitly specified. E.g. The scrolling behavior of an element can be
   // specified in CSS.
   virtual ScrollBehavior scrollBehaviorStyle() const {
@@ skipping 127 matching lines @@
   // 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