URLFetcher uses a TaskRunner instead of a message loop.

net/url_request/url_fetcher.h

Index: net/url_request/url_fetcher.h
diff --git a/net/url_request/url_fetcher.h b/net/url_request/url_fetcher.h
index ce29b303fe5ff9283ac11fbb48e5a490d6f34931..190e53932652eaa46f6a3450cc207b968c0ab97e 100644
--- a/net/url_request/url_fetcher.h
+++ b/net/url_request/url_fetcher.h
@@ -12,6 +12,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/platform_file.h"
 #include "base/supports_user_data.h"
+#include "base/task_runner.h"
 #include "net/base/net_export.h"
 
 class FilePath;
@@ -194,21 +195,21 @@ class NET_EXPORT URLFetcher {
 
   // By default, the response is saved in a string. Call this method to save the
   // response to a file instead. Must be called before Start().
-  // |file_message_loop_proxy| will be used for all file operations.
+  // |file_task_runner| will be used for all file operations.
   // To save to a temporary file, use SaveResponseToTemporaryFile().
   // The created file is removed when the URLFetcher is deleted unless you
   // take ownership by calling GetResponseAsFilePath().
   virtual void SaveResponseToFileAtPath(
       const FilePath& file_path,
-      scoped_refptr<base::MessageLoopProxy> file_message_loop_proxy) = 0;
+      scoped_refptr<base::TaskRunner> file_task_runner) = 0;
 
   // By default, the response is saved in a string. Call this method to save the
   // response to a temporary file instead. Must be called before Start().
-  // |file_message_loop_proxy| will be used for all file operations.
+  // |file_task_runner| will be used for all file operations.
   // The created file is removed when the URLFetcher is deleted unless you
   // take ownership by calling GetResponseAsFilePath().
   virtual void SaveResponseToTemporaryFile(
-      scoped_refptr<base::MessageLoopProxy> file_message_loop_proxy) = 0;
+      scoped_refptr<base::TaskRunner> file_task_runner) = 0;
 
   // Retrieve the response headers from the request.  Must only be called after
   // the OnURLFetchComplete callback has run.