Clear the owner element's widget in Document::shutdown().

third_party/WebKit/Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 2386 matching lines @@
   FrameNavigationDisabler navigationDisabler(*m_frame);
   // Defer widget updates to avoid plugins trying to run script inside
   // ScriptForbiddenScope, which will crash the renderer after
   // https://crrev.com/200984
   HTMLFrameOwnerElement::UpdateSuspendScope suspendWidgetHierarchyUpdates;
   // Don't allow script to run in the middle of detachLayoutTree() because a
   // detaching Document is not in a consistent state.
   ScriptForbiddenScope forbidScript;
 
   view()->dispose();
+
+  // If the widget of the document's frame owner doesn't match view() then
+  // FrameView::dispose() didn't clear the owner's widget. If we don't clear it
+  // here, it may be clobbered later in LocalFrame::createView(). See also
+  // https://crbug.com/673170 and the comment in FrameView::dispose().
+  HTMLFrameOwnerElement* ownerElement = m_frame->deprecatedLocalOwner();
+  if (ownerElement)
+    ownerElement->setWidget(nullptr);
+
   m_markers->prepareForDestruction();
 
   m_lifecycle.advanceTo(DocumentLifecycle::Stopping);
 
   if (page())
     page()->documentDetached(this);
   InspectorInstrumentation::documentDetached(this);
 
   if (m_frame->loader().client()->sharedWorkerRepositoryClient())
     m_frame->loader()
@@ skipping 4172 matching lines @@
 }
 
 void showLiveDocumentInstances() {
   WeakDocumentSet& set = liveDocumentSet();
   fprintf(stderr, "There are %u documents currently alive:\n", set.size());
   for (Document* document : set)
     fprintf(stderr, "- Document %p URL: %s\n", document,
             document->url().getString().utf8().data());
 }
 #endif