Provides an update link if theme/plugin/core updates are available.

function wp_admin_bar_updates_menu( $wp_admin_bar ) {

	$update_data = wp_get_update_data();

	if ( ! $update_data['counts']['total'] ) {
		return;
	}

	$updates_text = sprintf(
		/* translators: %s: Total number of updates available. */
		_n( '%s update available', '%s updates available', $update_data['counts']['total'] ),
		number_format_i18n( $update_data['counts']['total'] )
	);

	$icon   = '';
	$title  = '' . number_format_i18n( $update_data['counts']['total'] ) . '';
	$title .= '' . $updates_text . '';

	$wp_admin_bar->add_node(
		array(
			'id'    => 'updates',
			'title' => $icon . $title,
			'href'  => network_admin_url( 'update-core.php' ),
		)
	);
}