gdata: Implement periodic file system update checks.

chrome/browser/chromeos/extensions/file_browser_event_router.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_CHROMEOS_EXTENSIONS_FILE_BROWSER_EVENT_ROUTER_H_
 #define CHROME_BROWSER_CHROMEOS_EXTENSIONS_FILE_BROWSER_EVENT_ROUTER_H_
 #pragma once
 
 #include <map>
 #include <set>
@@ skipping 138 matching lines @@
       const chromeos::disks::DiskMountManager::MountPointInfo& mount_info);
 
   void RemoveBrowserFromVector(const std::string& path);
 
   // Used to create a window of a standard size, and add it to a list
   // of tracked browser windows in case that device goes away.
   void OpenFileBrowse(const std::string& url,
                       const std::string& device_path,
                       bool small);
 
+  // Returns the GDataFileSystem for the current profile.
+  gdata::GDataFileSystem* GetRemoteFileSystem() const;
+
+  // Handles requests to start and stop periodic updates on remote file system.
+  // When |start| is set to true, this function starts periodic updates only if
+  // it is not yet started; when |start| is set to false, this function stops
+  // periodic updates only if the number of outstanding update requests reaches
+  // zero.
+  void HandleRemoteUpdateRequestOnUIThread(bool start);
+
   scoped_refptr<FileWatcherDelegate> delegate_;
   WatcherMap file_watchers_;
   scoped_ptr<FileBrowserNotifications> notifications_;
   Profile* profile_;
   base::Lock lock_;
 
   bool current_gdata_operation_failed_;
   int last_active_gdata_operation_count_;
 
+  // Number of active update requests on the remote file system.
+  int num_remote_update_requests_;
+
   DISALLOW_COPY_AND_ASSIGN(FileBrowserEventRouter);
 };
 
 // Singleton that owns all FileBrowserEventRouter and associates
 // them with Profiles.
 class FileBrowserEventRouterFactory
     : public RefcountedProfileKeyedServiceFactory {
  public:
   // Returns the FileBrowserEventRouter for |profile|, creating it if
   // it is not yet created.
@@ skipping 11 matching lines @@
 
   FileBrowserEventRouterFactory();
   virtual ~FileBrowserEventRouterFactory();
 
   // ProfileKeyedServiceFactory:
   virtual scoped_refptr<RefcountedProfileKeyedService> BuildServiceInstanceFor(
       Profile* profile) const OVERRIDE;
 };
 
 #endif  // CHROME_BROWSER_CHROMEOS_EXTENSIONS_FILE_BROWSER_EVENT_ROUTER_H_