base/threading: measure event wait times

base/threading: measure event wait times

Before submitting a patch to make thread creations not to wait until the
newly created thread has started, measure event wait times on the thread
startup durations.

BUG=495097
Committed: https://crrev.com/c3609d0d3167350796ba2685c6444cacd18065a2
Cr-Commit-Position: refs/heads/master@{#340303}

[Takashi Toyoshima, 2015-07-24 11:43:34]

toyoshim@chromium.org changed reviewers:
+ thestig@chromium.org

[Takashi Toyoshima, 2015-07-24 11:44:36]

Can I add these measurement code before landing
https://codereview.chromium.org/1150563002/ ?

[Lei Zhang, 2015-07-24 18:54:34]

lgtm

[Lei Zhang, 2015-07-24 18:54:37]

The CQ bit was checked by thestig@chromium.org

[commit-bot: I haz the power, 2015-07-24 18:55:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1259603002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1259603002/1

[commit-bot: I haz the power, 2015-07-24 19:04:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-24 19:05:31]

Patchset 1 (id:??) landed as
https://crrev.com/c3609d0d3167350796ba2685c6444cacd18065a2
Cr-Commit-Position: refs/heads/master@{#340303}