Be more careful about exceptions in input callbacks.

consumeEvents() may be called reentrantly so we need to be
careful when handling exceptions.  When called directly
through JNI, the exception should be allowed to bubble up
to the caller.  When called from a Looper callback, the
exception should be recorded on the MessageQueue and bubbled
when the call to nativePollOnce() returns.

Bug: 6312938
Change-Id: Ief5e315802f586aa85af7eef1bd6e9bea4ce24ab