Implement Invalidator::Acknowledge

sync/notifier/invalidation_state_tracker.cc

Index: sync/notifier/invalidation_state_tracker.cc
diff --git a/sync/notifier/invalidation_state_tracker.cc b/sync/notifier/invalidation_state_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6dff75f2b1616a8f523241dedb3437ca9fc97359
--- /dev/null
+++ b/sync/notifier/invalidation_state_tracker.cc
@@ -0,0 +1,18 @@
+// 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.
+
+#include "sync/notifier/invalidation_state_tracker.h"
+
+namespace syncer {
+
+LocalState::LocalState()
+    : version(kint64min),
+      expected(AckHandle::InvalidAckHandle()),
+      current(AckHandle::InvalidAckHandle()) {
+}
+
+LocalState::~LocalState() {
+}
+
+}  // namespace syncer