Refactor sync-specific parts out of SyncNotifier/SyncNotifierObserver

sync/notifier/invalidation_util.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.
 //
 // Various utilities for dealing with invalidation data types.
 
 #ifndef SYNC_NOTIFIER_INVALIDATION_UTIL_H_
 #define SYNC_NOTIFIER_INVALIDATION_UTIL_H_
 #pragma once
 
@@ skipping 11 matching lines @@
 
 namespace syncer {
 
 struct ObjectIdLessThan {
   bool operator()(const invalidation::ObjectId& lhs,
                   const invalidation::ObjectId& rhs) const;
 };
 
 typedef std::set<invalidation::ObjectId, ObjectIdLessThan> ObjectIdSet;
 
+// TODO(dcheng): Should ModelType stuff be factored out of here?
 bool RealModelTypeToObjectId(syncer::ModelType model_type,
                              invalidation::ObjectId* object_id);
 
 bool ObjectIdToRealModelType(const invalidation::ObjectId& object_id,
                              syncer::ModelType* model_type);
 
+ObjectIdSet ModelTypeSetToObjectIdSet(const ModelTypeSet& models);
+ModelTypeSet ObjectIdSetToModelTypeSet(const ObjectIdSet& ids);
+
 std::string ObjectIdToString(const invalidation::ObjectId& object_id);
 
 std::string InvalidationToString(
     const invalidation::Invalidation& invalidation);
 
 }  // namespace syncer
 
 #endif  // SYNC_NOTIFIER_INVALIDATION_UTIL_H_