Merge "Add shadow to dream overlay home controls button." into udc-dev am: 3502d6ba am: 012b8e37 am: 7d21b274

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23146423



Change-Id: I204b88fea9dca675399432f28d2fa05628a5b544
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>