Merge "Use status bar appearance to determine header element brightness." into udc-qpr-dev am: f502b11399

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23517670

Change-Id: I520532f79dd62f03d208ed62c56ca34d74f19d5d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>