Add non-blocking sync code to ProfileSyncService

sync/internal_api/test/fake_sync_manager.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/internal_api/public/test/fake_sync_manager.h"
 
 #include <cstddef>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 200 matching lines @@
 
 void FakeSyncManager::ShutdownOnSyncThread() {
   DCHECK(sync_task_runner_->RunsTasksOnCurrentThread());
   test_user_share_.TearDown();
 }
 
 UserShare* FakeSyncManager::GetUserShare() {
   return test_user_share_.user_share();
 }
 
-syncer::SyncCore* FakeSyncManager::GetSyncCore() {
-  return NULL;
+base::WeakPtr<syncer::SyncCore> FakeSyncManager::GetSyncCore() {
+  return base::WeakPtr<syncer::SyncCore>();
 }
 
 const std::string FakeSyncManager::cache_guid() {
   return test_user_share_.user_share()->directory->cache_guid();
 }
 
 bool FakeSyncManager::ReceivedExperiment(Experiments* experiments) {
   return false;
 }
 
@@ skipping 19 matching lines @@
   return last_refresh_request_types_;
 }
 
 void FakeSyncManager::OnInvalidatorStateChange(InvalidatorState state) {
   // Do nothing.
 }
 
 std::string FakeSyncManager::GetOwnerName() const { return "FakeSyncManager"; }
 
 }  // namespace syncer