gdata: Implement periodic file system update checks.

chrome/browser/chromeos/extensions/file_browser_event_router.cc

Index: chrome/browser/chromeos/extensions/file_browser_event_router.cc
diff --git a/chrome/browser/chromeos/extensions/file_browser_event_router.cc b/chrome/browser/chromeos/extensions/file_browser_event_router.cc
index c3479feb361e067385b3f48596832237c6bd1297..4dac80630f1274a9d6a636449c66a67257d22561 100644
--- a/chrome/browser/chromeos/extensions/file_browser_event_router.cc
+++ b/chrome/browser/chromeos/extensions/file_browser_event_router.cc
@@ -166,6 +166,11 @@ bool FileBrowserEventRouter::AddFileWatch(
   } else {
     iter->second->AddExtension(extension_id);
   }
+  if (is_remote_watch) {
+    gdata::GDataFileSystem* file_system = GetFileSystem();
+    if (file_system)
+      file_system->StartUpdates();
+  }
   return true;
 }
 
@@ -179,6 +184,9 @@ void FileBrowserEventRouter::RemoveFileWatch(
   // their change notifications.
   if (gdata::util::GetSpecialRemoteRootPath().IsParent(watch_path)) {
     watch_path = gdata::util::ExtractGDataPath(watch_path);
+    gdata::GDataFileSystem* file_system = GetFileSystem();
+    if (file_system)
+      file_system->StopUpdates();
   }
   WatcherMap::iterator iter = file_watchers_.find(watch_path);
   if (iter == file_watchers_.end())
@@ -255,10 +263,7 @@ void FileBrowserEventRouter::MountCompleted(
     if ((event_type == DiskMountManager::MOUNTING) !=
         (error_code == chromeos::MOUNT_ERROR_NONE)) {
       FilePath source_path(mount_info.source_path);
-      gdata::GDataSystemService* system_service =
-          gdata::GDataSystemServiceFactory::GetForProfile(profile_);
-      gdata::GDataFileSystem* file_system =
-          system_service ? system_service->file_system() : NULL;
+      gdata::GDataFileSystem* file_system = GetFileSystem();
       if (file_system && file_system->IsUnderGDataCacheDirectory(source_path))
         file_system->SetMountedState(source_path, false,
                                      gdata::SetMountedStateCallback());
@@ -601,6 +606,12 @@ FileBrowserEventRouter::FileWatcherExtensions::GetVirtualPath() const {
   return virtual_path_;
 }
 
+gdata::GDataFileSystem* FileBrowserEventRouter::GetFileSystem() const {
+  gdata::GDataSystemService* system_service =
+      gdata::GDataSystemServiceFactory::GetForProfile(profile_);
+  return (system_service ? system_service->file_system() : NULL);
+}
+
 bool FileBrowserEventRouter::FileWatcherExtensions::Watch
     (const FilePath& path, FileWatcherDelegate* delegate) {
   if (is_remote_file_system_)