Let SyncManagerFactory create different types of sync managers according to

sync/internal_api/sync_manager_factory.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/sync_manager_factory.h"
 
+#include "sync/internal_api/sync_backup_manager.h"
 #include "sync/internal_api/sync_manager_impl.h"
+#include "sync/internal_api/sync_rollback_manager.h"
 
 namespace syncer {
 
-SyncManagerFactory::SyncManagerFactory() {
+SyncManagerFactory::SyncManagerFactory(SyncManagerFactory::MANAGER_TYPE type)
+    : type_(type) {
 }
 
 SyncManagerFactory::~SyncManagerFactory() {
 }
 
 scoped_ptr<SyncManager> SyncManagerFactory::CreateSyncManager(
       const std::string name) {
-  return scoped_ptr<SyncManager>(new SyncManagerImpl(name));
+  switch (type_) {
+    case NORMAL:
+      return scoped_ptr<SyncManager>(new SyncManagerImpl(name));
+    case BACKUP:
+      return scoped_ptr<SyncManager>(new SyncBackupManager);

[Nicolas Zea, 2014/05/13 17:49:15]

nit: prefer explicitly noting that this is being default constructed by
including parens

[haitaol1, 2014/05/13 18:10:59]

Done.

+    case ROLLBACK:
+      return scoped_ptr<SyncManager>(new SyncRollbackManager);
+    default:
+      NOTREACHED();
+  }
 }
 
 }  // namespace syncer