Add power_USBHotplugInSuspend to test USB device hotplugging during suspend.

This test suspends the DUT by running the client test power_KernelSuspend and
then uses servo to power on/off the USB key, simulating a hotplug insertion or
removal.  After the DUT resumes, the test verifies that the change was detected.

BUG=chromium-os:36015
TEST=Ran it

Change-Id: I13d4dd9870b02dc5b3e62ed20758da4d260d4b31
Reviewed-on: https://gerrit.chromium.org/gerrit/41328
Commit-Queue: Andrew Bresticker <abrestic@chromium.org>
Reviewed-by: Andrew Bresticker <abrestic@chromium.org>
Tested-by: Andrew Bresticker <abrestic@chromium.org>
2 files changed