Replace URLDataSource::MessageLoopForRequestPath() with TaskRunnerForRequestPath().

chrome/browser/thumbnails/thumbnail_list_source.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 "chrome/browser/thumbnails/thumbnail_list_source.h"
 
 #include <stddef.h>
 
 #include <string>
 
@@ skipping 83 matching lines @@
 std::string ThumbnailListSource::GetSource() const {
   return chrome::kChromeUIThumbnailListHost;
 }
 
 void ThumbnailListSource::StartDataRequest(
     const std::string& path,
     const content::ResourceRequestInfo::WebContentsGetter& wc_getter,
     const content::URLDataSource::GotDataCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (!top_sites_) {
-    callback.Run(NULL);
+    callback.Run(nullptr);
     return;
   }
 
   top_sites_->GetMostVisitedURLs(
       base::Bind(&ThumbnailListSource::OnMostVisitedURLsAvailable,
                  weak_ptr_factory_.GetWeakPtr(), callback),
       true);
 }
 
 std::string ThumbnailListSource::GetMimeType(const std::string& path) const {
   return "text/html";
 }
 
-base::MessageLoop* ThumbnailListSource::MessageLoopForRequestPath(
-    const std::string& path) const {
+scoped_refptr<base::SingleThreadTaskRunner>
+ThumbnailListSource::TaskRunnerForRequestPath(const std::string& path) const {
   // TopSites can be accessed from the IO thread.
-  return thumbnail_service_.get() ?
-      NULL : content::URLDataSource::MessageLoopForRequestPath(path);
+  return thumbnail_service_.get()
+             ? nullptr
+             : content::URLDataSource::TaskRunnerForRequestPath(path);
 }
 
 bool ThumbnailListSource::ShouldServiceRequest(
     const net::URLRequest* request) const {
   if (request->url().SchemeIs(chrome::kChromeSearchScheme))
     return InstantIOContext::ShouldServiceRequest(request);
   return URLDataSource::ShouldServiceRequest(request);
 }
 
 bool ThumbnailListSource::ShouldReplaceExistingSource() const {
@@ skipping 29 matching lines @@
   }
   if (num_mv_with_thumb < num_mv) {
     out.push_back("<h2>TopSites URLs without Thumbnails</h2>\n");
     RenderMostVisitedURLList(mvurl_list, base64_encoded_pngs, false, &out);
   }
   out.push_back(kHtmlFooter);
 
   std::string out_html = base::JoinString(out, base::StringPiece());
   callback.Run(base::RefCountedString::TakeString(&out_html));
 }