WP_Ajax_Upgrader_Skin::feedback( string|array|WP_Error $data )

	public function feedback( $data ) {
		if ( is_wp_error( $data ) ) {
			foreach ( $data->get_error_codes() as $error_code ) {
				$this->errors->add( $error_code, $data->get_error_message( $error_code ), $data->get_error_data( $error_code ) );
			}
		}

		$args = func_get_args();
		call_user_func_array( array( $this, 'parent::feedback' ), $args );
	}