Add return values to SyncerCommand

chrome/browser/sync/engine/apply_updates_command.h

Index: chrome/browser/sync/engine/apply_updates_command.h
diff --git a/chrome/browser/sync/engine/apply_updates_command.h b/chrome/browser/sync/engine/apply_updates_command.h
index d75754ffb4ca3cc2e418ed956c08d23605ec125c..fc7a42c80a301f269a4fc4b9b7761ac08be7f671 100644
--- a/chrome/browser/sync/engine/apply_updates_command.h
+++ b/chrome/browser/sync/engine/apply_updates_command.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -20,7 +20,7 @@ class ApplyUpdatesCommand : public ModelChangingSyncerCommand {
   // ModelChangingSyncerCommand implementation.
   virtual std::set<ModelSafeGroup> GetGroupsToChange(
       const sessions::SyncSession& session) const OVERRIDE;
-  virtual void ModelChangingExecuteImpl(
+  virtual SyncerError ModelChangingExecuteImpl(
       sessions::SyncSession* session) OVERRIDE;
 
  private: