GitLab

Tested using a brio-stream-4k-hd-webcam,
where we could change the exposure time in manual mode.

command line:
v4l2-ctl -d 1 --set-ctrl exposure_auto=1
v4l2-ctl -d 1 --set-ctrl exposure_absolute=100

GUI:
guvcview  --device=/dev/video1

TEST= run the demo in https://codepen.io/rijuB/pen/gjapBo
use slider to change exposureTime.

BUG=823316

Intent to Implement and Ship discussions:
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/ls3wQSoHOUY

Change-Id: I2c4faaf8bd475fedefd267aaf83e6c06f55e5afd
Reviewed-on: https://chromium-review.googlesource.com/c/1243288
Commit-Queue: Rijubrata Bhaumik <rijubrata.bhaumik@intel.com>
Reviewed-by: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603482}