I could move it into a TrackBuilder class, but it seems to be tightly coupled to the Track class, which is why I made it an inner static class.

I'm following how Android devs do it: http://developer.android.com/reference/android/app/Notification.Builder.html
and how we do it at my job: http://www.crashplan.com/

I don't really have any strong feelings to where the class should belong.