Add video_WebRtcPower and video_PowerConsumption test.

The video_WebRtcPower measures the power consumption of WebRTC loopback.
The video_PowerConsumption test turns off the AC power and runs the
video_WebRtcPower test.

BUG=chromium:391396
TEST=Run the test on peach_pit
CQ-DEPEND=CL:206995

Change-Id: I8749b73a4097dcad354e9de1ab919414f5e20043
Reviewed-on: https://chromium-review.googlesource.com/206963
Reviewed-by: Wu-Cheng Li <wuchengli@chromium.org>
Commit-Queue: Wen-Ding Li <wending@google.com>
Tested-by: Wen-Ding Li <wending@google.com>
5 files changed