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

	public function feedback( $data ) {
		if ( is_wp_error( $data ) ) {
			$string = $data->get_error_message();
		} elseif ( is_array( $data ) ) {
			return;
		} else {
			$string = $data;
		}
		if ( ! empty( $this->upgrader->strings[ $string ] ) )
			$string = $this->upgrader->strings[ $string ];

		if ( strpos( $string, '%' ) !== false ) {
			$args = func_get_args();
			$args = array_splice( $args, 1 );
			if ( ! empty( $args ) )
				$string = vsprintf( $string, $args );
		}

		$string = trim( $string );

		// Only allow basic HTML in the messages, as it'll be used in emails/logs rather than direct browser output.
		$string = wp_kses( $string, array(
			'a' => array(
				'href' => true
			),
			'br' => true,
			'em' => true,
			'strong' => true,
		) );

		if ( empty( $string ) )
			return;

		$this->messages[] = $string;
	}