Merge "Explicit Nullbility in Launcher (Part 2)" into tm-qpr-dev am: 775b0d21dc

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/19679564

Change-Id: Id2c74d88f52aa1dd9b0c22738f7f36c2b4d7afdf
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>