Merge "Set preference background color as transparent" into udc-dev am: 706cc584 am: 96f940bd am: cb3f44b3

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



Change-Id: I2bb7c52c502939950e41fc6c07f4c6284601b7b6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>