Abandon prerenders upon render thread shutdown.

third_party/WebKit/Source/platform/Prerender.h

 /*
  * Copyright (C) 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 65 matching lines @@
     ExtraData* getExtraData() { return m_extraData.get(); }
 
     void didStartPrerender();
     void didStopPrerender();
     void didSendLoadForPrerender();
     void didSendDOMContentLoadedForPrerender();
 
 private:
     Prerender(PrerenderClient*, const KURL&, unsigned relTypes, const Referrer&);
 
-    Member<PrerenderClient> m_client;
+    // The embedder's prerendering support holds on to pending Prerender objects;
+    // those references should not keep the PrerenderClient alive -- if the client
+    // becomes otherwise unreachable it should be GCed (at which point it will
+    // abandon this Prerender object.)
+    WeakMember<PrerenderClient> m_client;

[sof, 2016/04/18 11:33:53]

An alternative to this is to have the WebPrivatePtr<Prerender> be weak instead.

 
     const KURL m_url;
     const unsigned m_relTypes;
     const Referrer m_referrer;
 
     RefPtr<ExtraData> m_extraData;
 };
 
 } // namespace blink
 
 #endif // Prerender_h