Merge "Add a missing NULL check for postActivityStartTokenRemoval()" am: 5fea1d9a01 am: 1c691ff753

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1593831

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ib5ce8805a0d414a60958a83978dca5ce2598dd64