OverscrollGlow for mainThread-{BLINK CHANGES}

public/web/WebWidgetClient.h

Index: public/web/WebWidgetClient.h
diff --git a/public/web/WebWidgetClient.h b/public/web/WebWidgetClient.h
index 178c78efa715ec05e28b682b2f31deaa2c1ce711..8ab9df9a2cee364ad283f72d2bb888d78dbb9dfb 100644
--- a/public/web/WebWidgetClient.h
+++ b/public/web/WebWidgetClient.h
@@ -152,6 +152,9 @@ public:
     // Called when a gesture event is handled.
     virtual void didHandleGestureEvent(const WebGestureEvent& event, bool eventCancelled) { }
 
+    // Called when overscrolled on main thread.
+    virtual void didOverScrollOnMainThread(const float& unusedDeltaX, const float& unusedDeltaY, const float& accumaltedRootOverScrollX, const float& accumaltedRootOverScrollY, const float& positionX, const float& positionY, const float& velocityX, const float& velocityY) { }
+
     // Called to update if touch events should be sent.
     virtual void hasTouchEventHandlers(bool) { }