Function gio_2_0_sys::g_bus_watch_name_on_connection

pub unsafe extern "C" fn g_bus_watch_name_on_connection(
    connection: *mut GDBusConnection, 
    name: *const gchar, 
    flags: GBusNameWatcherFlags, 
    name_appeared_handler: Option<GBusNameAppearedCallback>, 
    name_vanished_handler: Option<GBusNameVanishedCallback>, 
    user_data: gpointer, 
    user_data_free_func: Option<GDestroyNotify>
) -> guint