In local_change:remote_change conflict case we may have no data in metadata_store

chrome/browser/sync_file_system/drive_file_sync_service.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_SYNC_FILE_SYSTEM_DRIVE_FILE_SYNC_SERVICE_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_FILE_SYNC_SERVICE_H_
 
 #include <deque>
 #include <map>
 #include <set>
@@ skipping 211 matching lines @@
   void DidRemoveOriginOnMetadataStore(
       scoped_ptr<TaskToken> token,
       const fileapi::SyncStatusCallback& callback,
       fileapi::SyncStatusCode status);
 
   void AppendNewRemoteChange(const GURL& origin,
                              google_apis::DocumentEntry* entry,
                              int64 changestamp);
   void CancelRemoteChange(const fileapi::FileSystemURL& url);
 
+  // This returns false if no change is found for the |url|.
+  bool GetPendingChangeForFileSystemURL(const fileapi::FileSystemURL& url,
+                                        RemoteChange* change) const;
+
   scoped_ptr<DriveMetadataStore> metadata_store_;
   scoped_ptr<DriveFileSyncClient> sync_client_;
 
   fileapi::SyncStatusCode last_operation_status_;
   RemoteServiceState state_;
   std::deque<base::Closure> pending_tasks_;
 
   int64 largest_changestamp_;
   PendingChangeQueue pending_changes_;
   URLToChange url_to_change_;
@@ skipping 10 matching lines @@
   // Use WeakPtrFactory instead of SupportsWeakPtr to revoke the weak pointer
   // in |token_|.
   base::WeakPtrFactory<DriveFileSyncService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DriveFileSyncService);
 };
 
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_FILE_SYNC_SERVICE_H_