Make scrollWidth and scrollHeight match other DOM measurement APIs

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 3357 matching lines @@
         return IntSize();
     LayoutView* root = page()->deprecatedLocalMainFrame()->contentRenderer();
     if (!root)
         return IntSize();
     return root->documentRect().size();
 }
 
 WebSize WebViewImpl::contentsPreferredMinimumSize()
 {
     Document* document = m_page->mainFrame()->isLocalFrame() ? m_page->deprecatedLocalMainFrame()->document() : 0;
-    if (!document || !document->layoutView() || !document->documentElement())
+    if (!document || !document->layoutView() || !document->documentElement() || !document->documentElement()->layoutBox())
         return WebSize();
 
     layout();
     int widthScaled = document->layoutView()->minPreferredLogicalWidth(); // Already accounts for zoom.
-    int heightScaled = static_cast<int>(document->documentElement()->scrollHeight() * zoomLevelToZoomFactor(zoomLevel()));
+    LayoutBox* documentBox = document->documentElement()->layoutBox();
+    // TODO(leviw): We truncate then zoom the height instead of rounding to match the width behavior. We
+    // should be able to call documentElement's scrollHeight() method. crbug.com/471336
+    int heightScaled = adjustLayoutUnitForAbsoluteZoom(documentBox->scrollHeight(), *documentBox).toInt() * zoomLevelToZoomFactor(zoomLevel());
     return IntSize(widthScaled, heightScaled);
 }
 
 void WebViewImpl::enableViewport()
 {
     settings()->setViewportEnabled(true);
 }
 
 void WebViewImpl::disableViewport()
 {
@@ skipping 1129 matching lines @@
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 void WebViewImpl::forceNextWebGLContextCreationToFail()
 {
     WebGLRenderingContext::forceNextWebGLContextCreationToFail();
 }
 
 } // namespace blink