Add CHECKs to ResourceLoader to investigate crashes

third_party/WebKit/Source/core/fetch/ResourceLoader.h

 /*
  * Copyright (C) 2005, 2006, 2011 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 106 matching lines @@
   FetchContext& context() const;
   ResourceRequestBlockedReason canAccessResponse(Resource*,
                                                  const ResourceResponse&) const;
 
   void cancelForRedirectAccessCheckError(const KURL&,
                                          ResourceRequestBlockedReason);
   void requestSynchronously(const ResourceRequest&);
 
   std::unique_ptr<WebURLLoader> m_loader;
   Member<ResourceFetcher> m_fetcher;
-  Member<Resource> m_resource;
+  const Member<Resource> m_resource;
   bool m_isCacheAwareLoadingActivated;
 };
 
 }  // namespace blink
 
 #endif