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

chrome/browser/search/thumbnail_source.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_SEARCH_THUMBNAIL_SOURCE_H_
 #define CHROME_BROWSER_SEARCH_THUMBNAIL_SOURCE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 29 matching lines @@
   ThumbnailSource(Profile* profile, bool capture_thumbnails);
   ~ThumbnailSource() override;
 
   // content::URLDataSource implementation.
   std::string GetSource() const override;
   void StartDataRequest(
       const std::string& path,
       const content::ResourceRequestInfo::WebContentsGetter& wc_getter,
       const content::URLDataSource::GotDataCallback& callback) override;
   std::string GetMimeType(const std::string& path) const override;
-  base::MessageLoop* MessageLoopForRequestPath(
+  scoped_refptr<base::SingleThreadTaskRunner> TaskRunnerForRequestPath(
       const std::string& path) const override;
   bool ShouldServiceRequest(const net::URLRequest* request) const override;
 
   // Extracts the |page_url| (e.g. cnn.com) and the |fallback_thumbnail_url|
   // fetchable from the server, if present, from the |path|. Visible for
   // testing.
   void ExtractPageAndThumbnailUrls(const std::string& path,
                                    GURL* page_url,
                                    GURL* fallback_thumbnail_url);
 
@@ skipping 24 matching lines @@
   // existing thumbnails in the database that contain a URL matching the prefix
   // of the requested URL.
   const bool capture_thumbnails_;
 
   base::WeakPtrFactory<ThumbnailSource> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ThumbnailSource);
 };
 
 #endif  // CHROME_BROWSER_SEARCH_THUMBNAIL_SOURCE_H_