The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/69ff2e79d39922b52b76c1f71cddb6d2f2597272

commit 69ff2e79d39922b52b76c1f71cddb6d2f2597272
Author: Peter Boström <pbos@chromium.org>
Date: Fri Jun 23 18:57:45 2017

Add support for querying min/max PTZ values.

Pan, tilt and zoom commands in chrome.webcamPrivate all use
device-specific ranges for argument values. To reasonably support
multiple cameras, or devices where PTZ ranges depend on firmware version
it makes sense to add support for querying ranges.

This adds support for V4L2, and the values are optional. If a camera
supports absolute pan for instance, then minPan and maxPan will be
available in the resultant struct. Same for tilt- zoom-equivalent
values.

Support for querying these values have not been added to VISCA as I do
not have this camera available. For this camera the range will currently
be absent.

BUG= chromium:734125 
R=tbarzic@chromium.org, zork@chromium.org

Change-Id: I75a004c5b971d238a6372f796000eebb7327f8a0
Reviewed-on: https://chromium-review.googlesource.com/544315
Commit-Queue: Peter Boström <pbos@chromium.org>
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Reviewed-by: Zachary Kuznia <zork@chromium.org>
Cr-Commit-Position: refs/heads/master@{#481976}
[modify] https://crrev.com/69ff2e79d39922b52b76c1f71cddb6d2f2597272/extensions/browser/api/webcam_private/v4l2_webcam.cc
[modify] https://crrev.com/69ff2e79d39922b52b76c1f71cddb6d2f2597272/extensions/browser/api/webcam_private/v4l2_webcam.h
[modify] https://crrev.com/69ff2e79d39922b52b76c1f71cddb6d2f2597272/extensions/browser/api/webcam_private/visca_webcam.cc
[modify] https://crrev.com/69ff2e79d39922b52b76c1f71cddb6d2f2597272/extensions/browser/api/webcam_private/visca_webcam_unittest.cc
[modify] https://crrev.com/69ff2e79d39922b52b76c1f71cddb6d2f2597272/extensions/browser/api/webcam_private/webcam.h
[modify] https://crrev.com/69ff2e79d39922b52b76c1f71cddb6d2f2597272/extensions/browser/api/webcam_private/webcam_private_api.h
[modify] https://crrev.com/69ff2e79d39922b52b76c1f71cddb6d2f2597272/extensions/browser/api/webcam_private/webcam_private_api_chromeos.cc
[modify] https://crrev.com/69ff2e79d39922b52b76c1f71cddb6d2f2597272/extensions/common/api/webcam_private.idl