check_ethernet: add PAUSE_FILE/TIME check

power_SuspendStress test will bring down the lab ethernet repeatedly
and often. This allows power_SuspendStress to communicate how long
it thinks it will be bouncing the link and thus can tell this script
when the test has completed (and should continue checking link state).

CQ-DEPEND=CL:653661
BUG=chromium:677572
TEST=manually invoke on local machine with "bash -x" to review flow.

Change-Id: I572074a4b5affd4a0079995356983b42a68c005c
Reviewed-on: https://chromium-review.googlesource.com/653662
Commit-Ready: Grant Grundler <grundler@chromium.org>
Tested-by: Grant Grundler <grundler@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>
1 file changed