[Sync] Let ModelTypeRegistry filter out initial download USS types.

components/sync/engine_impl/model_type_registry.cc

Index: components/sync/engine_impl/model_type_registry.cc
diff --git a/components/sync/engine_impl/model_type_registry.cc b/components/sync/engine_impl/model_type_registry.cc
index 9cb41202e4f30beeac6a850e57d3a3cc6da56226..72450f479134cda02b5a7c6de4a31b2a2d38057a 100644
--- a/components/sync/engine_impl/model_type_registry.cc
+++ b/components/sync/engine_impl/model_type_registry.cc
@@ -245,6 +245,16 @@ ModelTypeSet ModelTypeRegistry::GetInitialSyncEndedTypes() const {
   return result;
 }
 
+ModelTypeSet ModelTypeRegistry::GetInitialSyncDoneNonBlockingTypes() const {
+  ModelTypeSet types;
+  for (const auto& worker : model_type_workers_) {
+    if (worker->IsInitialSyncEnded()) {
+      types.Put(worker->GetModelType());
+    }
+  }
+  return types;
+}
+
 UpdateHandlerMap* ModelTypeRegistry::update_handler_map() {
   return &update_handler_map_;
 }