Added new DriveNotificationObserver interface which all observers of Google Drive invalidations sho…

chrome/browser/sync_file_system/drive_file_sync_service.cc

 // 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.
 
 #include "chrome/browser/sync_file_system/drive_file_sync_service.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 
@@ skipping 2161 matching lines @@
     }
     return;
   }
 
   if (may_have_unfetched_changes_ &&
       !metadata_store_->incremental_sync_origins().empty()) {
     FetchChangesForIncrementalSync();
   }
 }
 
+void DriveFileSyncService::CheckForUpdates() {
+  MaybeStartFetchChanges();
+}
+
 void DriveFileSyncService::FetchChangesForIncrementalSync() {
   scoped_ptr<TaskToken> token(GetToken(FROM_HERE, TASK_TYPE_DRIVE,
                                        "Fetching remote change list"));
   DCHECK(token);
   DCHECK(may_have_unfetched_changes_);
   DCHECK(pending_batch_sync_origins_.empty());
   DCHECK(!metadata_store_->incremental_sync_origins().empty());
 
   DVLOG(1) << "FetchChangesForIncrementalSync (start_changestamp:"
            << (largest_fetched_changestamp_ + 1) << ")";
@@ skipping 284 matching lines @@
       pending_batch_sync_origins_.insert(origin);
   }
   callback.Run(status, resource_id);
 }
 
 std::string DriveFileSyncService::sync_root_resource_id() {
   return metadata_store_->sync_root_directory();
 }
 
 }  // namespace sync_file_system