Merge cherrypicks of [9007989] into qt-c2f2-release

        @Override // Binder call

        public int revokeChallenge(IBinder token) {

            checkPermission(MANAGE_BIOMETRIC);

            mHandler.post(() -> {

                // TODO(b/137106905): Schedule binder calls in FaceService to avoid deadlocks.

                if (getCurrentClient() == null) {

                // if we aren't handling any other HIDL calls (mCurrentClient == null), revoke the

                // challenge right away.

                return startRevokeChallenge(token);

                    // if we aren't handling any other HIDL calls (mCurrentClient == null), revoke

                    // the challenge right away.

                    startRevokeChallenge(token);

                } else {

                // postpone revoking the challenge until we finish processing the current HIDL call.

                    // postpone revoking the challenge until we finish processing the current HIDL

                    // call.

                    mRevokeChallengePending = true;

                return Status.OK;

                }

            });

            return Status.OK;

        }

        @Override // Binder call