Under most circumstances, atexit handlers won't run on Android. The (only, to my knowledge) exception is a manual call to System.exit() because of some catastrophic failure. That can happen before any other shutdown has taken place though (including e.g. stopping message loops / background threads), which then leads to crashes in other, seemingly unrelated places (see e.g. issue 718166). If we want crashes, we should just throw an exception, which will at least give a more useful stack trace :)

So, we should:
1) Get rid of calls to System.exit(), replacing them with something that does proper cleanup (e.g. throwing an exception)
2) Make AtExitManager a no-op on Android, just to be on the safe side.

Thanks to Anthony for the investigation!