Make ResourceFetcher return Resources with LoadError instead of nullptrs.

third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp

 /*
  *  Copyright (C) 2004, 2006, 2008 Apple Inc. All rights reserved.
  *  Copyright (C) 2005-2007 Alexey Proskuryakov <ap@webkit.org>
  *  Copyright (C) 2007, 2008 Julien Chaffraix <jchaffraix@webkit.org>
  *  Copyright (C) 2008, 2011 Google Inc. All rights reserved.
  *  Copyright (C) 2012 Intel Corporation
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
  *  License as published by the Free Software Foundation; either
@@ skipping 1347 matching lines @@
 
 void XMLHttpRequest::didFail(const ResourceError& error)
 {
     NETWORK_DVLOG(1) << this << " didFail()";
     ScopedEventDispatchProtect protect(&m_eventDispatchRecursionLevel);
 
     // If we are already in an error state, for instance we called abort(), bail out early.
     if (m_error)
         return;
 
-    if (error.isCancellation()) {
+    if (error.isCancellation() && !error.isAccessCheck()) {
         handleDidCancel();
         return;
     }
 
     if (error.isTimeout()) {
         handleDidTimeout();
         return;
     }
 
     // Network failures are already reported to Web Inspector by ResourceLoader.
@@ skipping 376 matching lines @@
     visitor->traceWrappers(m_responseDocument);
     visitor->traceWrappers(m_responseArrayBuffer);
 }
 
 std::ostream& operator<<(std::ostream& ostream, const XMLHttpRequest* xhr)
 {
     return ostream << "XMLHttpRequest " << static_cast<const void*>(xhr);
 }
 
 } // namespace blink