Merge "Update deprecation documentation for onBackPressed" into tm-dev am: 4f774309

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/18090442



Change-Id: Ie472c611ece749d39db48a04de391e7ccf281564
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>