FrameView's size should be calculated based on contentWidth+scrollbarWidth

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 3213 matching lines @@
     updatePageDefinedViewportConstraints(mainFrameImpl()->frame()->document()->viewportDescription());
     m_pageScaleConstraintsSet.computeFinalConstraints();
 
     if (settings()->shrinksViewportContentToFit()) {
         int verticalScrollbarWidth = 0;
         if (view->verticalScrollbar() && !view->verticalScrollbar()->isOverlayScrollbar())
             verticalScrollbarWidth = view->verticalScrollbar()->width();
         m_pageScaleConstraintsSet.adjustFinalConstraintsToContentsSize(contentsSize(), verticalScrollbarWidth);
     }
 
-    if (pinchVirtualViewportEnabled())
-        mainFrameImpl()->frameView()->resize(m_pageScaleConstraintsSet.mainFrameSize(contentsSize()));
+    if (pinchVirtualViewportEnabled()) {
+        int contentAndScrollbarWidth = contentsSize().width();
+        if (view->verticalScrollbar() && !view->verticalScrollbar()->isOverlayScrollbar())
+            contentAndScrollbarWidth += view->verticalScrollbar()->width();
+
+        view->resize(m_pageScaleConstraintsSet.mainFrameSize(contentAndScrollbarWidth));
+    }
 
     float newPageScaleFactor = pageScaleFactor();
     if (m_pageScaleConstraintsSet.needsReset() && m_pageScaleConstraintsSet.finalConstraints().initialScale != -1) {
         newPageScaleFactor = m_pageScaleConstraintsSet.finalConstraints().initialScale;
         m_pageScaleConstraintsSet.setNeedsReset(false);
     }
     setPageScaleFactor(newPageScaleFactor);
 
     updateLayerTreeViewport();
 
@@ skipping 1227 matching lines @@
     const PageScaleConstraints& constraints = m_pageScaleConstraintsSet.pageDefinedConstraints();
 
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return false;
 
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 } // namespace blink