Ignore revealKeyguardIfBouncerPrepared request if Bouncer is null.

Conceptually, if the Bouncer is not yet instantiated, it is not prepared
so we should ignore the request.

Test: Existing unit tests passing
Bug: 154928953
Change-Id: Iaa61d65ab8fc056b9ac4566f43599e81a2024e92
1 file changed