OverscrollGlow for mainThread-{BLINK CHANGES}

Source/core/page/EventHandler.h

Index: Source/core/page/EventHandler.h
diff --git a/Source/core/page/EventHandler.h b/Source/core/page/EventHandler.h
index 4266830b7ca330aaa454781b9b280b50a311f10a..f23da7036b83590f74585cefb8b16bb97ea09d48 100644
--- a/Source/core/page/EventHandler.h
+++ b/Source/core/page/EventHandler.h
@@ -125,6 +125,10 @@ public:
 
     void resizeScrollableAreaDestroyed();
 
+    IntPoint unusedDelta() const;
+    IntPoint accumaltedRootOverScroll() const;
+    void resetOverScrollParams();
+
     IntPoint lastKnownMousePosition() const;
     Cursor currentMouseCursor() const { return m_currentMouseCursor; }
 
@@ -256,7 +260,7 @@ private:
     //            On output, if provided and a node was scrolled stopNode will point to that node.
     // delta - The delta to scroll by, in the units of the granularity parameter. (e.g. pixels, lines, pages, etc.)
     // absolutePoint - For wheel scrolls - the location, in absolute coordinates, where the event occured.
-    bool scroll(ScrollDirection, ScrollGranularity, Node* startNode = nullptr, Node** stopNode = nullptr, float delta = 1.0f, IntPoint absolutePoint = IntPoint());
+    bool scroll(ScrollDirection, ScrollGranularity, Node* startNode = nullptr, Node** stopNode = nullptr, float delta = 1.0f, IntPoint absolutePoint = IntPoint(), int* unusedDelta = nullptr);
 
     void customizedScroll(const Node& startNode, ScrollState&);
 
@@ -372,6 +376,10 @@ private:
     LayoutSize m_offsetFromResizeCorner; // In the coords of m_resizeScrollableArea.
 
     bool m_mousePositionIsUnknown;
+
+    IntPoint m_unusedDelta;
+    IntPoint m_accumulatedRootOverscroll;
+
     IntPoint m_lastKnownMousePosition;
     IntPoint m_lastKnownMouseGlobalPosition;
     IntPoint m_mouseDownPos; // In our view's coords.