Add missing global declaration

backup/moodle2/restore_expcontent_stepslib.php

@@ -55,7 +55,7 @@ class restore_expcontent_activity_structure_step extends restore_activity_struct
      * @param stdClass $data the expcontent data
      */
     protected function process_expcontent($data) {
-        global $DB;
+        global $DB, $USER;
 
         $data = (object) $data;
         $data->course = $this->get_courseid();