[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 1fccac4e7ce519ae232b7b76aaa3808e50d5e6a0..45a0a99a4bb3791e9865b78ef3f9cf0c51c40318 100644
--- a/sync/internal_api/public/sync_manager.h
+++ b/sync/internal_api/public/sync_manager.h
@@ -407,10 +407,15 @@ class SyncManager {
   virtual void UpdateEnabledTypes(
       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 std::string& handler_name,
       const ObjectIdSet& ids) = 0;
 
   // Put the syncer in normal mode ready to perform nudges and polls.