I think the original idea when fixing bug 840143 (https://github.com/mozilla-b2g/gaia/commit/aeb356fa352378c12774817feaf2672e07ed45bc) was not to reset the timezone when disabling automatic date&time on settings (which fires an init process), so probably we don't need to pass an onload callback in here?

Not 100% sure of this, though, maybe I'm missing something