Unfurl media player on AOD=>lockscreen wakeup

Clip MediaContainerView to round rect with new height
when ExpandableView#actualHeight updates

Bug: 213503823
Test: MediaContainerTest
Test: press power button to wakeup, media player unfurls
Test: press power button to sleep, media player furls up

Change-Id: I58101a307f31fd5a90f05674352aad00c234a5fa