Merge "Mark DataUsageState as nullable to avoid potential NPE risk" am: 0960af0bf3 am: 325b033f85

Original change: https://android-review.googlesource.com/c/platform/packages/apps/Settings/+/2217422

Change-Id: Ie9d5325556a31c72af3520879212e5fc526ea0dc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>