Alsa state chooser

[KaZeR]

> I can see how having the sound info in a stack might be 
> useful (marginally, really), but I can't see it justifying 
> the use of D-bus.  I wouldn't say never, but I really can't 
> think of any pressing reasons to want to know when the state 
> changes.  

First example on top of my head : you are listening to music via your
headset, and you unplug it : if in a public place, it might be convenient to
pause media player to avoid bothering your neighboors. My other phone
behaves like that and i find it convenient and respectful for the other
people.