Flesh out URLLoader's download_to_file function....

chrome/browser/renderer_host/resource_handler.h

 // Copyright (c) 2006-2008 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.
 
 // This is the browser side of the resource dispatcher, it receives requests
 // from the RenderProcessHosts, and dispatches them to URLRequests. It then
 // fowards the messages from the URLRequests back to the correct process for
 // handling.
 //
 // See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading
@@ skipping 62 matching lines @@
   // The response is complete.  The final response status is given.
   // Returns false if the handler is deferring the call to a later time.
   virtual bool OnResponseCompleted(int request_id,
                                    const URLRequestStatus& status,
                                    const std::string& security_info) = 0;
 
   // Signals that the request is closed (i.e. finished successfully, cancelled).
   // This is a signal that the associated URLRequest isn't valid anymore.
   virtual void OnRequestClosed() = 0;
 
+  // This notification is synthesized by the RedirectToFileResourceHandler
+  // to indicate progress of 'download_to_file' requests. OnReadCompleted
+  // calls are consumed by the RedirectToFileResourceHandler and replaced
+  // with OnDataDownloaded calls.
+  virtual void OnDataDownloaded(int request_id, int bytes_downloaded) {}
+
  protected:
   friend class ChromeThread;
   friend class DeleteTask<ResourceHandler>;
 
   virtual ~ResourceHandler() {}
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_RESOURCE_HANDLER_H_