[Sync] Enable adding notifier observers from ProfileSyncService

sync/notifier/object_id_payload_map.cc

Index: sync/notifier/object_id_payload_map.cc
diff --git a/sync/notifier/object_id_payload_map.cc b/sync/notifier/object_id_payload_map.cc
index 179f8bedd9ab86f6aec3d50f12aa40b02c0d11c3..19eed0c197d0af861c95843b7a47222e3f17b497 100644
--- a/sync/notifier/object_id_payload_map.cc
+++ b/sync/notifier/object_id_payload_map.cc
@@ -6,6 +6,25 @@
 
 namespace syncer {
 
+ObjectIdSet ObjectIdPayloadMapToSet(
+    const ObjectIdPayloadMap& id_payloads) {
+  ObjectIdSet ids;
+  for (ObjectIdPayloadMap::const_iterator it = id_payloads.begin();
+       it != id_payloads.end(); ++it) {
+    ids.insert(it->first);
+  }
+  return ids;
+}
+
+ObjectIdPayloadMap ObjectIdSetToPayloadMap(
+    ObjectIdSet ids, const std::string& payload) {
+  ObjectIdPayloadMap id_payloads;
+  for (ObjectIdSet::const_iterator it = ids.begin(); it != ids.end(); ++it) {
+    id_payloads[*it] = payload;
+  }
+  return id_payloads;
+}
+
 ModelTypePayloadMap ObjectIdPayloadMapToModelTypePayloadMap(
     const ObjectIdPayloadMap& id_payloads) {
   ModelTypePayloadMap types_with_payloads;