Implement new invalidations ack tracking system

sync/notifier/p2p_invalidator.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/p2p_invalidator.h"
 
 #include <algorithm>
 #include <iterator>
 
 #include "base/json/json_reader.h"
@@ skipping 162 matching lines @@
       send_notification_target_,
       ObjectIdInvalidationMap::InvalidateAll(ids));
   SendNotificationData(notification_data);
 }
 
 void P2PInvalidator::UnregisterHandler(InvalidationHandler* handler) {
   DCHECK(thread_checker_.CalledOnValidThread());
   registrar_.UnregisterHandler(handler);
 }
 
-void P2PInvalidator::Acknowledge(const invalidation::ObjectId& id,
-                                 const AckHandle& ack_handle) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  // Do nothing for the P2P implementation.
-}
-
 InvalidatorState P2PInvalidator::GetInvalidatorState() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return registrar_.GetInvalidatorState();
 }
 
 void P2PInvalidator::UpdateCredentials(
     const std::string& email, const std::string& token) {
   DCHECK(thread_checker_.CalledOnValidThread());
   notifier::Subscription subscription;
   subscription.channel = kSyncP2PNotificationChannel;
@@ skipping 89 matching lines @@
     return;
   }
   notifier::Notification notification;
   notification.channel = kSyncP2PNotificationChannel;
   notification.data = notification_data.ToString();
   DVLOG(1) << "Sending XMPP notification: " << notification.ToString();
   push_client_->SendNotification(notification);
 }
 
 }  // namespace syncer