Make largest_changestamp setter/getter asynchronous.

chrome/browser/chromeos/drive/drive_feed_loader.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_DRIVE_DRIVE_FEED_LOADER_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_FEED_LOADER_H_
 
 #include <string>
 
 #include "base/callback_forward.h"
@@ skipping 101 matching lines @@
                                                DriveFileError error);
 
   // Helper callback for handling results of metadata retrieval initiated from
   // ReloadFromServerIfNeeded(). This method makes a decision about fetching
   // the content of the root feed during the root directory refresh process.
   void OnGetAccountMetadata(
       const FileOperationCallback& callback,
       google_apis::GDataErrorCode status,
       scoped_ptr<google_apis::AccountMetadataFeed> account_metadata);
 
+  // Callback for DriveResourceMetadata::GetLargestChangestamp.
+  // Compares |remote_changestamp| and |local_changestamp| and triggers
+  // LoadFromServer if necessary.
+  void CompareChangestampsAndLoadIfNeeded(
+      const FileOperationCallback& callback,
+      int64 remote_changestamp,
+      int64 local_changestamp);
+
   // Callback for handling response from |DriveAPIService::GetApplicationInfo|.
   // If the application list is successfully parsed, passes the list to
   // Drive webapps registry.
   void OnGetApplicationList(google_apis::GDataErrorCode status,
                             scoped_ptr<base::Value> json);
 
   // Callback for handling feed content fetching while searching for file info.
   // This callback is invoked after async feed fetch operation that was
   // invoked by StartDirectoryRefresh() completes. This callback will update
   // the content of the refreshed directory object and continue initially
@@ skipping 38 matching lines @@
 
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate its weak pointers before any other members are destroyed.
   base::WeakPtrFactory<DriveFeedLoader> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(DriveFeedLoader);
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_FEED_LOADER_H_