ui: Cleanup class/struct forward declarations

components/sync/model/mock_model_type_store.cc

Index: components/sync/model/mock_model_type_store.cc
diff --git a/components/sync/model/mock_model_type_store.cc b/components/sync/model/mock_model_type_store.cc
index ac2a9d272590204e83c5ea225f98337ced47b191..73b512c3ea0a96cb2026ae22cd79ac07c6f48524 100644
--- a/components/sync/model/mock_model_type_store.cc
+++ b/components/sync/model/mock_model_type_store.cc
@@ -46,9 +46,8 @@ void MockModelTypeStore::ReadAllMetadata(const ReadMetadataCallback& callback) {
     read_all_metadata_handler_.Run(callback);
   } else {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE,
-        base::Bind(callback, Result::SUCCESS,
-                   base::Passed(std::unique_ptr<RecordList>()), std::string()));
+        FROM_HERE, base::Bind(callback, SyncError(),
+                              base::Passed(std::unique_ptr<MetadataBatch>())));
   }
 }