public function update_backup_info($post_id, FW_Backup_Info $backup_info)
 {
     $now = time();
     if (!$backup_info->get_created_at()) {
         $backup_info->set_created_at($now);
     }
     $backup_info->set_updated_at($now);
     update_post_meta($post_id, 'backup_info', $backup_info);
 }