Add histogram owner for cookie DB loading.

Add histogram owner for cookie DB loading.

These histograms are related to SQLite load times and
specifically the registry controlled domains.

TBR=asvitkine@chromium.org
BUG=370672
NOTRY=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289466

[nyquist, 2014-08-14 05:06:58]

rsleevi/ollel: FYI. The stats for cookie loading look amazingly good after the
patch from ollel@

[nyquist, 2014-08-14 05:07:25]

asvitkine: TBRing adding histogram owner.

[nyquist, 2014-08-14 05:07:42]

The CQ bit was checked by nyquist@chromium.org

[commit-bot: I haz the power, 2014-08-14 05:12:29]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/nyquist@chromium.org/470043002/1

[commit-bot: I haz the power, 2014-08-14 05:18:06]

Committed patchset #1 (1) as 289466

[Alexei Svitkine (slow), 2014-08-14 14:55:40]

lgtm

[Olle Liljenzin, 2014-08-14 15:04:12]

On 2014/08/14 05:06:58, nyquist OOO - back Aug 19 wrote:
> rsleevi/ollel: FYI. The stats for cookie loading look amazingly good after the
> patch from ollel@

This is good to hear!

Not sure if "amazingly good" means load time improved or if the slowdown is just
not as bad as feared?

[nyquist, 2014-08-15 07:46:00]

Load times seem to be low and stable.