AndroidAsync : Synchronize isCancelled

The parent reference can be null between the check for not null and
and invocation on its method under extreme race conditions. Avoid
that by placing it inside a synchronized block.

Change-Id: Ib625847c23230cf2c42204325de54149026ff5c6
Merge "AndroidAsync : Synchronize isCancelled" into cm-11.0
Catch cancelled key exceptions.
Eat data on http client connect cancellation.
Add keySet method for HashedList.

Change-Id: I7a15d1e8ecdd58c3b853c7d51ea17574da7d7102