WordPress at a glance
action is not described

admin_bar_init action-hook . WP 3.1.0

Fires after WP_Admin_Bar is initialized.

Usage

add_action( 'admin_bar_init', 'action_function_name_5784' );
function action_function_name_5784(){
	// action...
}

Where the hook is called

WP_Admin_Bar::initialize()
admin_bar_init
wp-includes/class-wp-admin-bar.php 80
do_action( 'admin_bar_init' );

Where the hook is used (in WP core)

Does not used.