Require 'CHROME_HEADLESS' to use 'git-number'.

Require 'CHROME_HEADLESS' to use 'git-number'.

Updated 'git-number' to produce an error message if it's run without the
CHROME_HEADLESS (bot) environment variable. This is intended to alert developers
who may be incorrectly using this tool to get positioning information instead of
the commit position.

BUG=409917
TEST=local
  - Ran with and without 'CHROME_HEADLESS'; observed the error message in the
    'without' case.

R=iannucci@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=291773

[dnj, 2014-09-02 20:08:53]

Poke, let's close this :)

[iannucci, 2014-09-02 20:39:16]

lgtm

https://codereview.chromium.org/534703002/diff/1/git_number.py
File git_number.py (right):

https://codereview.chromium.org/534703002/diff/1/git_number.py#newcode256
git_number.py:256: if not os.getenv('CHROME_HEADLESS'):
if os.getenv('CHROME_HEADLESS') != '1':

[dnj, 2014-09-02 20:46:13]

https://codereview.chromium.org/534703002/diff/1/git_number.py
File git_number.py (right):

https://codereview.chromium.org/534703002/diff/1/git_number.py#newcode256
git_number.py:256: if not os.getenv('CHROME_HEADLESS'):
On 2014/09/02 20:39:16, iannucci wrote:
> if os.getenv('CHROME_HEADLESS') != '1':

Done.

[dnj, 2014-09-02 20:47:42]

The CQ bit was checked by dnj@chromium.org

[commit-bot: I haz the power, 2014-09-02 20:48:11]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dnj@chromium.org/534703002/20001

[commit-bot: I haz the power, 2014-09-02 20:50:00]

Committed patchset #2 (id:20001) as 291773