Add sync manager classes for backup/rollback:

sync/internal_api/sync_backup_manager.h

Index: sync/internal_api/sync_backup_manager.h
diff --git a/sync/internal_api/sync_backup_manager.h b/sync/internal_api/sync_backup_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..1bee105cdad4c711a208d7987f15ea21657ea24d
--- /dev/null
+++ b/sync/internal_api/sync_backup_manager.h
@@ -0,0 +1,69 @@
+// Copyright 2014 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.
+
+#ifndef SYNC_INTERNAL_API_SYNC_BACKUP_MANAGER_H_
+#define SYNC_INTERNAL_API_SYNC_BACKUP_MANAGER_H_
+
+#include <set>
+
+#include "sync/internal_api/sync_rollback_manager_base.h"
+
+namespace syncer {
+
+// SyncBackupManager runs before user signs in to sync to back up user's data
+// before sync starts. The data that's backed up can be used to restore user's
+// settings to pre-sync state.
+class SYNC_EXPORT_PRIVATE SyncBackupManager : public SyncRollbackManagerBase {
+ public:
+  SyncBackupManager();
+  virtual ~SyncBackupManager();
+
+  // SyncManager implementation.
+  virtual void Init(
+      const base::FilePath& database_location,
+      const WeakHandle<JsEventHandler>& event_handler,
+      const std::string& sync_server_and_path,
+      int sync_server_port,
+      bool use_ssl,
+      scoped_ptr<HttpPostProviderFactory> post_factory,
+      const std::vector<scoped_refptr<ModelSafeWorker> >& workers,
+      ExtensionsActivity* extensions_activity,
+      SyncManager::ChangeDelegate* change_delegate,
+      const SyncCredentials& credentials,
+      const std::string& invalidator_client_id,
+      const std::string& restored_key_for_bootstrapping,
+      const std::string& restored_keystore_key_for_bootstrapping,
+      InternalComponentsFactory* internal_components_factory,
+      Encryptor* encryptor,
+      scoped_ptr<UnrecoverableErrorHandler> unrecoverable_error_handler,
+      ReportUnrecoverableErrorFunction
+          report_unrecoverable_error_function,
+      CancelationSignal* cancelation_signal) OVERRIDE;
+  virtual void SaveChanges() OVERRIDE;
+  virtual SyncStatus GetDetailedStatus() const OVERRIDE;
+
+  // DirectoryChangeDelegate implementation.
+  virtual ModelTypeSet HandleTransactionEndingChangeEvent(
+      const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
+      syncable::BaseTransaction* trans) OVERRIDE;
+
+ private:
+  // Replaces local IDs with server IDs and clear unsynced bit of modified
+  // entries.
+  void NormalizeEntries();
+
+  // Handles of unsynced entries caused by local model changes.
+  std::set<int64> unsynced_;
+
+  // True if NormalizeEntries() is being called.
+  bool in_normalization_;
+
+  SyncStatus status_;
+
+  DISALLOW_COPY_AND_ASSIGN(SyncBackupManager);
+};
+
+}  // namespace syncer
+
+#endif  // SYNC_INTERNAL_API_SYNC_BACKUP_MANAGER_H_