Refactor ModelTypePayloadMap and ObjectIdPayloadMap to StateMaps.

sync/notifier/object_id_state_map_test_util.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SYNC_NOTIFIER_OBJECT_ID_STATE_MAP_TEST_UTILH_
+#define SYNC_NOTIFIER_OBJECT_ID_STATE_MAP_TEST_UTILH_
+
+// Convince googletest to use the correct overload for PrintTo().
+#include "sync/internal_api/public/base/invalidation_state_test_util.h"
+#include "sync/notifier/object_id_state_map.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace syncer {
+
+::testing::Matcher<const ObjectIdStateMap&> Eq(
+    const ObjectIdStateMap& expected);
+
+}  // namespace syncer
+
+#endif  // SYNC_NOTIFIER_OBJECT_ID_STATE_MAP_TEST_UTILH_