/**
  * Handles Live Updates for Stream Activity Dashboard Widget.
  *
  * @uses gather_updated_items
  *
  * @param  array  Response to heartbeat
  * @param  array  Response from heartbeat
  *
  * @return array  Data sent to heartbeat
  */
 public static function live_update($response, $data)
 {
     if (!isset($data['wp-stream-heartbeat-last-time'])) {
         return;
     }
     $send = array();
     $last_time = $data['wp-stream-heartbeat-last-time'];
     $updated_items = WP_Stream_Live_Update::gather_updated_items($last_time);
     if (!empty($updated_items)) {
         ob_start();
         foreach ($updated_items as $item) {
             echo self::widget_row($item);
             //xss okay
         }
         $send = ob_get_clean();
     }
     return $send;
 }