Merge "[a11y] When multi-user switcher is selected in lockscreen and Talkback is enabled, play helpful explanation." into tm-qpr-dev am: 168133e3eb am: 432c0bb3d8

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/19135806

Change-Id: I8e8353b5ae17eac6bba2c11371fae737482dae0c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>