On Ice Cream Sandwich, something -- possibly even in the Android
framework classes (not in our code) -- is passing in null to a
MessageListAdapter's unregisterOnDataSetObserver(), which causes a
crash.
We should really find out whether this is something we can properly fix
or not, but in the meantime, wrap the superclass's method with our own
method which checks for null before calling through to the superclass
implementation.
66006cabf5