Add Custom Links to Admin Menu Bar

In functions.php

add_action('admin_bar_menu', 'add_toolbar_items', 40);

    function add_toolbar_items($admin_bar){
    $admin_bar->add_menu( array(
        'id'    => 'parent',
        'title' => 'Title of the link',
        'href'  => '#',
        'meta'  => array(
            'title' => __('Links'),            
        ),
    ));

    $admin_bar->add_menu( array(
        'id'     => 'google',
        'parent' => 'parent',
        'title'  => 'Go To Google',
        'href'   => 'http://www.google.com',
        'meta'   => array(
            'title' => __('Google'),
            'class' => 'google'
        ),
    ));

}