Refactor the error state

Currently calling getError() will return whatever
is in the TextView, even if it is animating out,
which doesn't quite match developer expectation.

This CL updates the state so that it always returns
whatever the last call to setError() was.

BUG: 25781427
Change-Id: I359c271f31a7c3f26ed71b673f9797ce9d769e2e
1 file changed