Allow CertNetFetcher to be shutdown from the network thread

net/test/url_request/url_request_hanging_read_job.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/test/url_request/url_request_hanging_read_job.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 74 matching lines @@
   raw_headers.append(
       "HTTP/1.1 200 OK\n"
       "Content-type: text/plain\n");
   raw_headers.append(
       base::StringPrintf("Content-Length: %1d\n", content_length_));
   info->headers = new HttpResponseHeaders(HttpUtil::AssembleRawHeaders(
       raw_headers.c_str(), static_cast<int>(raw_headers.length())));
 }
 
 void URLRequestHangingReadJob::StartAsync() {
+  if (is_done())
+    return;
   set_expected_content_size(content_length_);
   NotifyHeadersComplete();
 }
 
 // static
 void URLRequestHangingReadJob::AddUrlHandler() {
   // Add |hostname| to URLRequestFilter for HTTP and HTTPS.
   URLRequestFilter* filter = URLRequestFilter::GetInstance();
   filter->AddHostnameInterceptor("http", kMockHostname,
                                  base::MakeUnique<MockJobInterceptor>());
   filter->AddHostnameInterceptor("https", kMockHostname,
                                  base::MakeUnique<MockJobInterceptor>());
 }
 
 // static
 GURL URLRequestHangingReadJob::GetMockHttpUrl() {
   return GetMockUrl("http", kMockHostname);
 }
 
 // static
 GURL URLRequestHangingReadJob::GetMockHttpsUrl() {
   return GetMockUrl("https", kMockHostname);
 }
 
 }  // namespace net