Merge "Fix potential NPE when preference is null" am: 2b6a72ba1f

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2256881

Change-Id: Ib0f7d5c73cd27c36f68844a9e9d3494dc2421aac
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>