c_g_bus_watch_name_on_connection

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
__gshared extern (C)
guint function(GDBusConnection* connection, gchar* name, GBusNameWatcherFlags flags, GBusNameAppearedCallback nameAppearedHandler, GBusNameVanishedCallback nameVanishedHandler, void* userData, GDestroyNotify userDataFreeFunc) c_g_bus_watch_name_on_connection;

Meta