[Sync] Rely on directory to decide which types need to be purged

sync/test/engine/test_syncable_utils.cc

Index: sync/test/engine/test_syncable_utils.cc
diff --git a/sync/test/engine/test_syncable_utils.cc b/sync/test/engine/test_syncable_utils.cc
index 8eb247f29ccb05ba52a2cbdc77d2e704b090212e..aeb4c6605e740bb75d2edccff9d61ea055e455da 100644
--- a/sync/test/engine/test_syncable_utils.cc
+++ b/sync/test/engine/test_syncable_utils.cc
@@ -90,5 +90,12 @@ void CreateTypeRoot(WriteTransaction* trans,
   node.PutSpecifics(specifics);
 }
 
+sync_pb::DataTypeProgressMarker BuildProgress(ModelType type) {
+  sync_pb::DataTypeProgressMarker progress;
+  progress.set_token("token");
+  progress.set_data_type_id(GetSpecificsFieldNumberFromModelType(type));
+  return progress;
+}
+
 }  // namespace syncable
 }  // namespace syncer