OverscrollGlow for mainThread-{BLINK CHANGES}

Source/platform/scroll/ScrollTypes.h

 /*
  * Copyright (C) 2006 Apple Computer, 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 175 matching lines @@
         , unusedScrollDelta(0) { }
     ScrollResultOneDimensional(bool didScroll, float unusedScrollDelta)
         : didScroll(didScroll)
         , unusedScrollDelta(unusedScrollDelta) { }
 
     bool didScroll;
     float unusedScrollDelta;
 };
 
 struct ScrollResult {
-    explicit ScrollResult(bool didScroll)
-        : didScroll(didScroll)
+    explicit ScrollResult()
+        : didScrollX(false)
+        , didScrollY(false)
         , unusedScrollDeltaX(0)
         , unusedScrollDeltaY(0) { }
-    ScrollResult(bool didScroll, float unusedScrollDeltaX, float unusedScrollDeltaY)
-        : didScroll(didScroll)
+    ScrollResult(bool didScrollX, bool didScrollY, float unusedScrollDeltaX, float unusedScrollDeltaY)
+        : didScrollX(didScrollX)
+        , didScrollY(didScrollY)
         , unusedScrollDeltaX(unusedScrollDeltaX)
         , unusedScrollDeltaY(unusedScrollDeltaY) { }
 
-    bool didScroll;
+    bool didScroll() { return didScrollX || didScrollY; }
+
+    bool didScrollX;
+    bool didScrollY;
     float unusedScrollDeltaX;
     float unusedScrollDeltaY;
 };
 
 typedef unsigned ScrollbarControlPartMask;
 
 }
 
 #endif