Function drmgr_register_low_on_memory_event_user_data 

pub unsafe extern "C" fn drmgr_register_low_on_memory_event_user_data(
    func: Option<unsafe extern "C" fn(user_data: *mut c_void)>,
    priority: *mut drmgr_priority_t,
    user_data: *mut c_void,
) -> bool_

Registers a callback function \p func for the low-on-memory event just like drmgr_register_low_on_memory_event(), but allows the passing of user data \p user_data. The callback is prioritised according to \p priority. \return whether successful.