OverscrollGlow for mainThread-{BLINK CHANGES}

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 50 matching lines @@
     WTF_MAKE_NONCOPYABLE(ScrollableArea);
 public:
     static int pixelsPerLineStep();
     static float minFractionToStepWhenPaging();
     static int maxOverlapBetweenPages();
 
     // The window that hosts the ScrollableArea. The ScrollableArea will communicate scrolls and repaints to the
     // host window in the window's coordinate space.
     virtual HostWindow* hostWindow() const { return 0; };
 
-    virtual bool scroll(ScrollDirection, ScrollGranularity, float delta = 1);
+    virtual ScrollResultOneDimensional scroll(ScrollDirection, ScrollGranularity, float delta = 1);
     virtual void setScrollPosition(const DoublePoint&, ScrollBehavior = ScrollBehaviorInstant);
     void scrollToOffsetWithoutAnimation(const FloatPoint&, bool cancelProgrammaticAnimations = true);
     void scrollToOffsetWithoutAnimation(ScrollbarOrientation, float offset);
 
     // Scrolls the area so that the given rect, given in the document's content coordinates, such that it's
     // visible in the area. Returns the new location of the input rect relative once again to the document.
     // Note, in the case of a Document container, such as FrameView, the output will always be the input rect
     // since scrolling it can't change the location of content relative to the document, unlike an overflowing
     // element.
     virtual LayoutRect scrollIntoView(const LayoutRect& rectInContent, const ScrollAlignment& alignX, const ScrollAlignment& alignY);
@@ skipping 272 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