Merge "Clarify that `Message#what` is 0 unless otherwise set." into main am: 14a533a83d

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/3250153

Change-Id: I3aa059317fadab9a204338d57b91b973fd7668a1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>