Add company link to the WordPress logo menu.

functions.admin_bar_menu.dev_branding_in_wp_logo_menu.php

<?php

/**
 * code to be placed in theme functions.php
 * add_filter priority of 10 or greater.
 */
if ( ! function_exists( 'mytheme_admin_bar_menu' ) ) {
	function mytheme_admin_bar_menu( $wp_admin_bar ) {
		$wp_admin_bar->add_node( array(
			'parent' => 'wp-logo-external',
			'id'     => 'acme-corp',
			'title'  => 'Acme Corp.',
			'href'   => 'http://acme.localhost/',
			'meta'   => array( 'title' => 'Acme Corporation', 'target' => '_blank' ),
		) );
	}
	add_filter( 'admin_bar_menu', 'mytheme_admin_bar_menu', 10 );
}