Update host visibility whenever lockscreen state changes Flag: EXEMPT BUGFIX Bug: 478725173 Test: atest KeyguardMediaControllerTest Test: atest MediaCarouselControllerTest (cherry picked from commit f0b9a17ddc990000d37ee188efe7f729c59a488d) Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:cf7776ba1db241f352ab87b5b1e4ee4f7c60df48 Merged-In: If1f6535574bfb3840705ab751976e61cadab01d6 Change-Id: If1f6535574bfb3840705ab751976e61cadab01d6