[Fetch, Loader] Expect on-heap objects will never get destroyed with a reference

third_party/WebKit/Source/core/loader/DocumentThreadableLoader.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013, Intel Corporation
  *
  * 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.
@@ skipping 629 matching lines @@
   // Remove any headers that may have been added by the network layer that cause
   // access control to fail.
   crossOriginRequest.clearHTTPReferrer();
   crossOriginRequest.clearHTTPOrigin();
   crossOriginRequest.clearHTTPUserAgent();
   // Add any CORS simple request headers which we previously saved from the
   // original request.
   for (const auto& header : m_simpleRequestHeaders)
     crossOriginRequest.setHTTPHeaderField(header.key, header.value);
   makeCrossOriginAccessRequest(crossOriginRequest);
-  // |this| may be dead here.
 
   return false;
 }
 
 void DocumentThreadableLoader::redirectBlocked() {
   m_checker.redirectBlocked();
 
   // Tells the client that a redirect was received but not followed (for an
   // unknown reason).
   ThreadableLoaderClient* client = m_client;
@@ skipping 295 matching lines @@
 
   // Prevent handleSuccessfulFinish() from bypassing access check.
   m_actualRequest = ResourceRequest();
 
   ThreadableLoaderClient* client = m_client;
   clear();
   client->didFailAccessControlCheck(error);
 }
 
 void DocumentThreadableLoader::handleError(const ResourceError& error) {
-  // Copy the ResourceError instance to make it sure that the passed
-  // ResourceError is alive during didFail() even when the Resource is
-  // destructed during didFail().
-  ResourceError copiedError = error;
-
   ThreadableLoaderClient* client = m_client;
   clear();
-  client->didFail(copiedError);
+  client->didFail(error);
 }
 
 void DocumentThreadableLoader::loadRequestAsync(
     const ResourceRequest& request,
     ResourceLoaderOptions resourceLoaderOptions) {
   if (!m_actualRequest.isNull())
     resourceLoaderOptions.dataBufferingPolicy = BufferData;
 
   if (m_options.timeoutMilliseconds > 0) {
     m_timeoutTimer.startOneShot(m_options.timeoutMilliseconds / 1000.0,
@@ skipping 153 matching lines @@
 }
 
 DEFINE_TRACE(DocumentThreadableLoader) {
   visitor->trace(m_resource);
   visitor->trace(m_document);
   ThreadableLoader::trace(visitor);
   RawResourceClient::trace(visitor);
 }
 
 }  // namespace blink