Add metrics OWNERS for extension_function_histogram_value.h.

Add metrics OWNERS for extension_function_histogram_value.h.

Changes to extension_function_histogram_value.h require changing
tools/metrics/histograms/histograms/histograms.xml, but this is not
being enforced.

NOTRY=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=262946

[Lei Zhang, 2014-04-08 17:28:28]

The extensions::functions::HistogramValue enum says:

// Last entry: Add new entries above and ensure to update
// tools/metrics/histograms/histograms/histograms.xml.

But this is repeatedly disregarded:
https://codereview.chromium.org/180163009
https://codereview.chromium.org/203753002
https://codereview.chromium.org/219333002

OWNERS is one way to enforce this. WDYT?

[Mark P, 2014-04-08 17:52:16]

On 2014/04/08 17:28:28, Lei Zhang wrote:
> The extensions::functions::HistogramValue enum says:
> 
> // Last entry: Add new entries above and ensure to update
> // tools/metrics/histograms/histograms/histograms.xml.
> 
> But this is repeatedly disregarded:
> https://codereview.chromium.org/180163009
> https://codereview.chromium.org/203753002
> https://codereview.chromium.org/219333002
> 
> OWNERS is one way to enforce this. WDYT?

Frankly, I'm not too worried about people not updating
histograms.xml as long as when someone gets around
to updating it later they get the enum values correct.

So, I'm not sure we need to be as heavy-handed as
an OWNERS file.

That said, more rarely the people delete old entries
or mess up the order of entries.  Maybe this is a
reason to do OWNERS review .  (How often does it
happen?)

I just don't want the process to slow down the people
who work on extensions, so if this isn't actually
necessary, I'm inclined to not add the OWNERS
restriction.

--mark

[Lei Zhang, 2014-04-08 17:58:52]

Anyone who updates extension_function_histogram_value.h should be updating
histograms.xml at the same time. So they should get a metrics OWNERS review
anyway.

Instead what's happening now is some people are skipping the metrics OWNERS
review, and others who try to do the right thing have to make the changes on
behalf of people who did not. Example with me here:
https://codereview.chromium.org/224963010/diff/40001/tools/metrics/histograms...

and then I rebased and found out I get to fix more missing enums:
https://codereview.chromium.org/224963010/diff/100001/tools/metrics/histogram...

[miket_OOO, 2014-04-08 18:15:53]

LGTM but please give Renaud a chance to weigh in.

[Lei Zhang, 2014-04-08 18:43:25]

An alternative is to have a presubmit check to verify the values in the two
files match up, but in most cases, a metrics owner needs to approve anyway.

[rpaquay, 2014-04-09 03:03:44]

lgtm

[Lei Zhang, 2014-04-10 06:07:39]

The CQ bit was checked by thestig@chromium.org

[commit-bot: I haz the power, 2014-04-10 06:07:42]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/thestig@chromium.org/228643006/1

[commit-bot: I haz the power, 2014-04-10 06:08:39]

Change committed as 262946