Do not invalidate listview just to update one time

Suspected mLapsAdapter.notifyDataSetChanged() was a key contributor to bug
7289174, but that proved not the case. This change does eliminate unneeded
view repaints in the listview.
Included some clean-ups.

Change-Id: I76e4698e17e3b8c6b1f988f09f96c7f7ec783d53