Update histograms.xml for UseCounters.

Update histograms.xml for UseCounters.

This updates histograms.xml for the UseCounter added in
https://codereview.chromium.org/1017903003

BUG=none

Committed: https://crrev.com/00d0f85879b47a030fadb74353b920b0b48d4177
Cr-Commit-Position: refs/heads/master@{#322023}

[davidben, 2015-03-24 00:33:33]

davidben@chromium.org changed reviewers:
+ isherman@chromium.org

[Ilya Sherman, 2015-03-24 00:37:26]

lgtm

[davidben, 2015-03-24 00:49:29]

The CQ bit was checked by davidben@chromium.org

[commit-bot: I haz the power, 2015-03-24 00:50:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1010083005/1

[commit-bot: I haz the power, 2015-03-24 06:51:04]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-24 06:51:05]

Try jobs failed on following builders:
  linux_android_rel_ng on tryserver.chromium.linux (JOB_TIMED_OUT,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_android_r...)
Timed out jobs are not retried to avoid causing additional load on the builders
with large pending queues.

[davidben, 2015-03-24 16:36:38]

The CQ bit was checked by davidben@chromium.org

[commit-bot: I haz the power, 2015-03-24 16:36:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1010083005/1

[commit-bot: I haz the power, 2015-03-24 17:27:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-24 17:27:57]

Patchset 1 (id:??) landed as
https://crrev.com/00d0f85879b47a030fadb74353b920b0b48d4177
Cr-Commit-Position: refs/heads/master@{#322023}