Merge "Prevent NPE in NavigationBar" into sc-v2-dev am: 43057f8d5c am: 0bb1e39ff1

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15886625

Change-Id: Ic93fb26be6538b91baaf859f7fdf4cedbff5fdeb