Merge "Set preference background color as transparent" into udc-dev am: 706cc584 am: 96f940bd

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23008277



Change-Id: I8466c868e71767c9d0012e67528603dcdb7e3e37
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>