Create DeviceBase class.

The structure of DUT and instrument class is similar, so we created
a DeviceBase class as their parent class.

BUG=none
TEST=none

Change-Id: If35b28d8490d63a6dd2b918b8079bc32f8303a10
Reviewed-on: https://chromium-review.googlesource.com/456183
Commit-Ready: Chih-Yu Huang <akahuang@chromium.org>
Tested-by: Chih-Yu Huang <akahuang@chromium.org>
Reviewed-by: Joel Kitching <kitching@chromium.org>
3 files changed