Convert main-thread overscroll parameters into viewport space.

third_party/WebKit/public/web/WebWidgetClient.h

 /*
  * Copyright (C) 2009 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 115 matching lines @@
     // including when a lock is pending but not yet acquired.
     // WebWidget::didLosePointerLock() is called when unlock is complete.
     virtual void requestPointerUnlock() { }
 
     // Returns true iff the pointer is locked to this widget.
     virtual bool isPointerLocked() { return false; }
 
     // Called when a gesture event is handled.
     virtual void didHandleGestureEvent(const WebGestureEvent& event, bool eventCancelled) { }
 
-    // Called when overscrolled on main thread.
-    virtual void didOverscroll(const WebFloatSize& unusedDelta, const WebFloatSize& accumulatedRootOverScroll, const WebFloatPoint& position, const WebFloatSize& velocity) { }
+    // Called when overscrolled on main thread. All parameters are in
+    // viewport-space.
+    virtual void didOverscroll(
+        const WebFloatSize& overscrollDelta,
+        const WebFloatSize& accumulatedOverscroll,
+        const WebFloatPoint& positionInViewport,
+        const WebFloatSize& velocityInViewport) { }
 
     // Called to update if touch events should be sent.
     virtual void hasTouchEventHandlers(bool) { }
 
     // Called during WebWidget::HandleInputEvent for a TouchStart event to inform the embedder
     // of the touch actions that are permitted for this touch.
     virtual void setTouchAction(WebTouchAction touchAction) { }
 
     // Called when value of focused text field gets dirty, e.g. value is
     // modified by script, not by user input.
@@ skipping 37 matching lines @@
     // migration is completed.
     virtual void convertWindowToViewport(WebFloatRect* rect) {}
 
 protected:
     ~WebWidgetClient() { }
 };
 
 } // namespace blink
 
 #endif