Early out of registerViewportLayerWithCompositor if there's no local MainFrame.

third_party/WebKit/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 4175 matching lines @@
 }
 
 bool WebViewImpl::tabsToLinks() const
 {
     return m_tabsToLinks;
 }
 
 void WebViewImpl::registerViewportLayersWithCompositor()
 {
     DCHECK(m_layerTreeView);
-    DCHECK(page()->deprecatedLocalMainFrame());
+
+    if (!page()->mainFrame() || !page()->mainFrame()->isLocalFrame())
+        return;
 
     Document* document = page()->deprecatedLocalMainFrame()->document();
 
     DCHECK(document);
 
     // Get the outer viewport scroll layer.
     GraphicsLayer* layoutViewportScrollLayer =
         document->rootScrollerController()->rootScrollerLayer();
     WebLayer* layoutViewportWebLayer = layoutViewportScrollLayer
         ? layoutViewportScrollLayer->platformLayer()
@@ skipping 364 matching lines @@
 {
     // TODO(oshima): Investigate if this should return the ScreenInfo's scale factor rather than
     // page's scale factor, which can be 1 in use-zoom-for-dsf mode.
     if (!page())
         return 1;
 
     return page()->deviceScaleFactor();
 }
 
 } // namespace blink