Added an optional on_exit to the autotest stressor library.

BUG=None
TEST=stress_unittest.py

Change-Id: Ia12be63c96114076b85ecdad0e6def064969fd60
Reviewed-on: https://gerrit.chromium.org/gerrit/38430
Reviewed-by: Prashanth Balasubramanian <beeps@chromium.org>
Reviewed-by: Kris Rambish <krisr@chromium.org>
Commit-Ready: Craig Harrison <craigdh@chromium.org>
Tested-by: Craig Harrison <craigdh@chromium.org>
2 files changed