[Sync] Avoid unregistering object IDs on shutdown

sync/internal_api/public/sync_manager.h

Index: sync/internal_api/public/sync_manager.h
diff --git a/sync/internal_api/public/sync_manager.h b/sync/internal_api/public/sync_manager.h
index f36b8ec8b49e1752976fc2849acfc134f9a85bf7..cf49e928ab575cf316b3416784828d0fa0d123d9 100644
--- a/sync/internal_api/public/sync_manager.h
+++ b/sync/internal_api/public/sync_manager.h
@@ -407,9 +407,14 @@ class SyncManager {
       const ModelTypeSet& enabled_types) = 0;
 
   // Forwards to the underlying notifier (see
+  // SyncNotifier::SetHandler()).
+  virtual void SetInvalidationHandler(
+      const std::string& handler_name, SyncNotifierObserver* handler) = 0;
+
+  // Forwards to the underlying notifier (see
   // SyncNotifier::UpdateRegisteredIds()).
   virtual void UpdateRegisteredInvalidationIds(
-      SyncNotifierObserver* handler, const ObjectIdSet& ids) = 0;
+      const std::string& handler_name, const ObjectIdSet& ids) = 0;
 
   // Put the syncer in normal mode ready to perform nudges and polls.
   virtual void StartSyncingNormally(