Optimize posting of WTF::Closure and improve scheduler test mocks

content/child/web_url_loader_impl.cc

 // Copyright 2014 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 "content/child/web_url_loader_impl.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 1150 matching lines @@
   context_->SetDefersLoading(value);
 }
 
 void WebURLLoaderImpl::didChangePriority(WebURLRequest::Priority new_priority,
                                          int intra_priority_value) {
   context_->DidChangePriority(new_priority, intra_priority_value);
 }
 
 void WebURLLoaderImpl::setLoadingTaskRunner(
     blink::WebTaskRunner* loading_task_runner) {
-  context_->SetTaskRunner(loading_task_runner->taskRunner());
+  context_->SetTaskRunner(loading_task_runner->toSingleThreadTaskRunner());
 }
 
 // This function is implemented here because it uses net functions. it is
 // tested in
 // third_party/WebKit/Source/core/fetch/MultipartImageResourceParserTest.cpp.
 bool WebURLLoaderImpl::ParseMultipartHeadersFromBody(
     const char* bytes,
     size_t size,
     blink::WebURLResponse* response,
     size_t* end) {
@@ skipping 31 matching lines @@
     response->clearHTTPHeaderField(webStringName);
     while (response_headers->EnumerateHeader(&iterator, name, &value)) {
       response->addHTTPHeaderField(webStringName,
                                    WebString::fromLatin1(value));
     }
   }
   return true;
 }
 
 }  // namespace content