Merge "Remove light theme support for split screen surface." into udc-dev am: 9779b22c

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22955244



Change-Id: I442cae24dcbdd8ed658ae97f0c76059342da5383
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>