Add a force-layout-height-to-zero layout mode to WebViewImpl

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 3031 matching lines @@
     if (settings()->viewportEnabled()) {
         layoutSize = flooredIntSize(m_pageScaleConstraintsSet.pageDefinedConstraints().layoutSize);
 
         bool textAutosizingEnabled = page()->settings().textAutosizingEnabled();
         if (textAutosizingEnabled && layoutSize.width != view->layoutSize().width()) {
             if (TextAutosizer* textAutosizer = page()->deprecatedLocalMainFrame()->document()->textAutosizer())
                 textAutosizer->recalculateMultipliers();
         }
     }
 
+    if (page()->settings().forceZeroLayoutHeight())
+        layoutSize.height = 0;

[abarth-chromium, 2014/07/29 16:54:55]

The settings machinery looks fine, but I don't understand the consequences of
this part of the CL.  We'll need to get someone who understands this line to
complete the review.

[mkosiba (inactive), 2014/07/29 16:57:43]

Thanks! I'll ask Alex to take a look.

+
     view->setLayoutSize(layoutSize);
 }
 
 IntSize WebViewImpl::contentsSize() const
 {
     if (!page()->mainFrame()->isLocalFrame())
         return IntSize();
     RenderView* root = page()->deprecatedLocalMainFrame()->contentRenderer();
     if (!root)
         return IntSize();
@@ skipping 1117 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