Function gst_app_src_simple_callbacks_set_need_data 

pub unsafe extern "C" fn gst_app_src_simple_callbacks_set_need_data(
    cb: *mut GstAppSrcSimpleCallbacks,
    need_data_cb: GstAppSrcNeedDataCallback,
    user_data: gpointer,
    destroy_notify: GDestroyNotify,
)

Available on crate feature v1_28 only.