[Sync] Avoid unregistering object IDs on shutdown

sync/notifier/sync_notifier_factory_unittest.cc

Index: sync/notifier/sync_notifier_factory_unittest.cc
diff --git a/sync/notifier/sync_notifier_factory_unittest.cc b/sync/notifier/sync_notifier_factory_unittest.cc
index 8036c1a172170d66b9298344c7427e0752753074..50d923bb7ee11159e897529b96b700c0934d93fb 100644
--- a/sync/notifier/sync_notifier_factory_unittest.cc
+++ b/sync/notifier/sync_notifier_factory_unittest.cc
@@ -61,8 +61,9 @@ TEST_F(SyncNotifierFactoryTest, Basic) {
 #else
   ASSERT_TRUE(notifier.get());
   ObjectIdSet ids = ModelTypeSetToObjectIdSet(ModelTypeSet(syncer::BOOKMARKS));
+  notifier->RegisterHandler(&mock_observer_);
   notifier->UpdateRegisteredIds(&mock_observer_, ids);
-  notifier->UpdateRegisteredIds(&mock_observer_, ObjectIdSet());
+  notifier->UnregisterHandler(&mock_observer_);
 #endif
 }
 
@@ -79,8 +80,9 @@ TEST_F(SyncNotifierFactoryTest, Basic_P2P) {
 #else
   ASSERT_TRUE(notifier.get());
   ObjectIdSet ids = ModelTypeSetToObjectIdSet(ModelTypeSet(syncer::BOOKMARKS));
+  notifier->RegisterHandler(&mock_observer_);
   notifier->UpdateRegisteredIds(&mock_observer_, ids);
-  notifier->UpdateRegisteredIds(&mock_observer_, ObjectIdSet());
+  notifier->UnregisterHandler(&mock_observer_);
 #endif
 }