Move stressor object into loop so its destroyed.

The threading module will throw and exception if subclass objects
are not destroyed before they attempt to run again.

TEST=Ran it
BUG=None

Change-Id: Ib45f027fe08c1fe4cf629df4f1af34d8e07502b1
Reviewed-on: https://gerrit.chromium.org/gerrit/39405
Tested-by: Kris Rambish <krisr@chromium.org>
Reviewed-by: Craig Harrison <craigdh@chromium.org>
Commit-Ready: Kris Rambish <krisr@chromium.org>
1 file changed