Merge "Remove Dream Overlay when Dream Window detaches." into tm-qpr-dev am: fd0d46e0

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/20889203



Change-Id: Idd32ec86f55bb0d1cce8a9b355c845a6a5739d79
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>