periodic_scheduler: add a basic sanity test

BUG=chromium:375989
TEST=`FEATURES=test emerge-amd64-generic chromeos-init` passes
TEST=`./periodic_scheduler_unittest` with older periodic_scheduler fails

Change-Id: I2aa91022baf8215862ec7de81300ef1c71520525
Reviewed-on: https://chromium-review.googlesource.com/201496
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
2 files changed