tree 094a5c1410c8807829e2b7c49473046576344d88
parent 0b1b1c434650d2f272be7610027d4ddd948715a8
author Bryce Lee <brycelee@google.com> 1495493844 -0700
committer Bryce Lee <brycelee@google.com> 1496159043 -0700

Check for source activity's task presence before referencing.

ActivityStarter guards in all other spots for a null task in the
source activity, which can be the case if said activity is finishing.

This changelist adds the same check to the code when processing a
finishing source.

Change-Id: I78c284f45d96348767d06bb6ce0d78d6b77cb0ad
Fixes: 37428712
Test: manual testing & code inspection
Test: go/wm-smoke