Implement new invalidations ack tracking system

sync/notifier/unacked_invalidation_set_test_util.h

+// Copyright 2013 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.
+
+#include "sync/notifier/unacked_invalidation_set.h"
+
+#include "testing/gmock/include/gmock/gmock-matchers.h"
+
+namespace syncer {
+
+namespace test_util {
+
+void PrintTo(const UnackedInvalidationSet& invalidations, ::std::ostream* os);
+
+void PrintTo(const UnackedInvalidationsMap& map, ::std::ostream* os);
+
+::testing::Matcher<const UnackedInvalidationSet&> Eq(
+    const UnackedInvalidationSet& expected);
+
+::testing::Matcher<const UnackedInvalidationsMap&> Eq(
+    const UnackedInvalidationsMap& expected);
+
+}  // namespace test_util
+
+}  // namespace syncer