Merge "Remove Dream Overlay when Dream Window detaches." into tm-qpr-dev am: fd0d46e023 am: 390e7025f0

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

Change-Id: I0c8f085262469e3e07b5699eaf502cb28952a07e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>