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

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

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I8860761993c9a4b9ebb45c8d3f54d58b205926e4