Return AUTHENTICATION_FAILED error if Drive operation has failed and user is not signed in

chrome/browser/sync_file_system/drive_file_sync_service.h

Index: chrome/browser/sync_file_system/drive_file_sync_service.h
diff --git a/chrome/browser/sync_file_system/drive_file_sync_service.h b/chrome/browser/sync_file_system/drive_file_sync_service.h
index 04ddeffcb4f1dcac5ab94f7a447c0ba291094eb3..adeb56025cc9982645b0a4f12eed6459eecb30c3 100644
--- a/chrome/browser/sync_file_system/drive_file_sync_service.h
+++ b/chrome/browser/sync_file_system/drive_file_sync_service.h
@@ -287,6 +287,11 @@ class DriveFileSyncService
   bool GetPendingChangeForFileSystemURL(const fileapi::FileSystemURL& url,
                                         RemoteChange* change) const;
 
+  // A wrapper implementation to GDataErrorCodeToSyncStatusCode which returns
+  // authentication error if the user is not signed in.
+  fileapi::SyncStatusCode GDataErrorCodeToSyncStatusCodeWrapper(
+      google_apis::GDataErrorCode error) const;
+
   FilePath temporary_file_dir_;
 
   scoped_ptr<DriveMetadataStore> metadata_store_;