Implement new invalidations ack tracking system

sync/notifier/invalidation_state_tracker.cc

-// 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 {
-
-InvalidationState::InvalidationState()
-    : version(kint64min),
-      expected(AckHandle::InvalidAckHandle()),
-      current(AckHandle::InvalidAckHandle()) {
-}
-
-InvalidationState::~InvalidationState() {
-}
-
-bool operator==(const InvalidationState& lhs, const InvalidationState& rhs) {
-  return lhs.version == rhs.version &&
-      lhs.expected.Equals(rhs.expected) &&
-      lhs.current.Equals(rhs.current);
-}
-
-}  // namespace syncer