Mac: Update scrollbar size and input position during impl-overscroll

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 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 4289 matching lines @@
 
 void WebViewImpl::applyViewportDeltas(
     const WebSize& pinchViewportDelta,
     const WebSize& mainFrameDelta,
     const WebFloatSize& elasticOverscrollDelta,
     float pageScaleDelta,
     float topControlsDelta)
 {
     ASSERT(pinchVirtualViewportEnabled());
 
-    if (!mainFrameImpl() || !mainFrameImpl()->frameView())
+    if (!mainFrameImpl())
+        return;
+    FrameView* frameView = mainFrameImpl()->frameView();
+    if (!frameView)
         return;
 
     setTopControlsContentOffset(m_topControlsContentOffset + topControlsDelta);
 
     FloatPoint pinchViewportOffset = page()->frameHost().pinchViewport().visibleRect().location();
     pinchViewportOffset.move(pinchViewportDelta.width, pinchViewportDelta.height);
     setPageScaleFactorAndLocation(pageScaleFactor() * pageScaleDelta, pinchViewportOffset);
 
     if (pageScaleDelta != 1)
         m_doubleTapZoomPending = false;
 
+    frameView->setElasticOverscroll(elasticOverscrollDelta + frameView->elasticOverscroll());
+
     IntPoint mainFrameScrollOffset = IntPoint(mainFrame()->scrollOffset());
     mainFrameScrollOffset.move(mainFrameDelta.width, mainFrameDelta.height);
     updateMainFrameScrollPosition(mainFrameScrollOffset, false);
 }
 
 void WebViewImpl::applyViewportDeltas(const WebSize& scrollDelta, float pageScaleDelta, float topControlsDelta)
 {
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return;
 
@@ skipping 170 matching lines @@
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 void WebViewImpl::forceNextWebGLContextCreationToFail()
 {
     WebGLRenderingContext::forceNextWebGLContextCreationToFail();
 }
 
 } // namespace blink