Run load state update timer only when needed

content/browser/loader/resource_dispatcher_host_impl.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.
 
 // This is the browser side of the resource dispatcher, it receives requests
 // from the child process (i.e. [Renderer, Plugin, Worker]ProcessHost), and
 // dispatches them to URLRequests. It then forwards 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 476 matching lines @@
   // specified |id|.
   void RegisterResourceMessageDelegate(const GlobalRequestID& id,
                                        ResourceMessageDelegate* delegate);
   void UnregisterResourceMessageDelegate(const GlobalRequestID& id,
                                          ResourceMessageDelegate* delegate);
 
   int BuildLoadFlagsForRequest(const ResourceHostMsg_Request& request_data,
                                int child_id,
                                bool is_sync_load);
 
+  // Schedules UpdateLoadInfo() to be invoked after a delay (for coalescing).
+  // This is only necessary when a page is loading or if there is an upload in
+  // progress. We want to avoid repeatedly calling this when we have a "hanging
+  // get" request like when on a Google Docs document.
+  void ScheduleUpdateLoadInfo();
+
   LoaderMap pending_loaders_;
 
   // Collection of temp files downloaded for child processes via
   // the download_to_file mechanism. We avoid deleting them until
   // the client no longer needs them.
   typedef std::map<int, scoped_refptr<storage::ShareableFileReference> >
       DeletableFilesMap;  // key is request id
   typedef std::map<int, DeletableFilesMap>
       RegisteredTempFiles;  // key is child process id
   RegisteredTempFiles registered_temp_files_;
 
-  // A timer that periodically calls UpdateLoadStates while pending_requests_
-  // is not empty.
-  scoped_ptr<base::RepeatingTimer<ResourceDispatcherHostImpl> >
+  // A timer for scheduling a call to UpdateLoadInfo after a delay.
+  scoped_ptr<base::OneShotTimer<ResourceDispatcherHostImpl> >
       update_load_states_timer_;
 
   // We own the save file manager.
   scoped_refptr<SaveFileManager> save_file_manager_;
 
   // Request ID for browser initiated requests. request_ids generated by
   // child processes are counted up from 0, while browser created requests
   // start at -2 and go down from there. (We need to start at -2 because -1 is
   // used as a special value all over the resource_dispatcher_host for
   // uninitialized variables.) This way, we no longer have the unlikely (but
@@ skipping 60 matching lines @@
   DelegateMap delegate_map_;
 
   scoped_ptr<ResourceScheduler> scheduler_;
 
   DISALLOW_COPY_AND_ASSIGN(ResourceDispatcherHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_RESOURCE_DISPATCHER_HOST_IMPL_H_