Add an uma stat to time Pending Tree activation

Add an uma stat to time Pending Tree activation

Adds an uma stat which tracks pending tree activation. Updated CC's
histogram macros to have a timer-only version of the area timer concept.

BUG=
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Committed: https://crrev.com/d69647a96ab9567614091a939be30e8a4330ba25
Cr-Commit-Position: refs/heads/master@{#396053}

[ericrk, 2016-04-13 00:56:38]

Description was changed from

==========
Add an uma stat to time Pending Tree activation

Adds an uma stat which tracks pending tree activation. Updated CC's
histogram macros to have a timer-only version of the area timer concept.

BUG=
==========

to

==========
Add an uma stat to time Pending Tree activation

Adds an uma stat which tracks pending tree activation. Updated CC's
histogram macros to have a timer-only version of the area timer concept.

BUG=
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
==========

[ericrk, 2016-05-23 22:34:44]

ericrk@chromium.org changed reviewers:
+ vmiura@chromium.org

[vmiura, 2016-05-23 22:58:38]

lgtm

[ericrk, 2016-05-24 17:49:19]

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

[ericrk, 2016-05-24 17:49:20]

Here's another UMA stat, thanks!

[Ilya Sherman, 2016-05-25 00:11:11]

lgtm

[ericrk, 2016-05-25 22:28:37]

The CQ bit was checked by ericrk@chromium.org

[commit-bot: I haz the power, 2016-05-25 22:30:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1878323004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1878323004/20001

[commit-bot: I haz the power, 2016-05-26 00:29:30]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-05-26 00:32:29]

Description was changed from

==========
Add an uma stat to time Pending Tree activation

Adds an uma stat which tracks pending tree activation. Updated CC's
histogram macros to have a timer-only version of the area timer concept.

BUG=
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
==========

to

==========
Add an uma stat to time Pending Tree activation

Adds an uma stat which tracks pending tree activation. Updated CC's
histogram macros to have a timer-only version of the area timer concept.

BUG=
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Committed: https://crrev.com/d69647a96ab9567614091a939be30e8a4330ba25
Cr-Commit-Position: refs/heads/master@{#396053}
==========

[commit-bot: I haz the power, 2016-05-26 00:32:30]

Patchset 2 (id:??) landed as
https://crrev.com/d69647a96ab9567614091a939be30e8a4330ba25
Cr-Commit-Position: refs/heads/master@{#396053}