Add missing histograms entry for GPU process startup time.

Add missing histograms entry for GPU process startup time.

Added way back in http://crrev.com/131691, but never had an XML
entry added so it would show up on the dashboard!

This means the UMA was logged (I think), but is not visible on
dashboards. Found while working on http://crrev.com/1805163002

BUG=none
TEST=none

Committed: https://crrev.com/4d29aa7b57b7297baabb45524ee205d4d35d4e35
Cr-Commit-Position: refs/heads/master@{#382104}

[DaleCurtis, 2016-03-17 20:56:15]

dalecurtis@chromium.org changed reviewers:
+ jwd@chromium.org, piman@chromium.org

[DaleCurtis, 2016-03-17 20:56:16]

+piman to vouch for who should be the owner of this UMA. I copied vangelis@ from
the similarly named one above.

[piman, 2016-03-17 23:11:43]

vangelis doesn't work on Chromium any more... Put me instead?

[DaleCurtis, 2016-03-17 23:20:45]

Done. Made you the owner of GPU.GPUProcessLaunchCause too since that was the
only other one vangelis@ owned.

[piman, 2016-03-17 23:33:26]

lgtm

[DaleCurtis, 2016-03-18 16:31:12]

Friendly ping jwd@.

[jwd, 2016-03-18 20:29:21]

lgtm

[DaleCurtis, 2016-03-18 20:29:35]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2016-03-18 20:30:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1812073002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1812073002/20001

[commit-bot: I haz the power, 2016-03-18 21:58:21]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-03-18 22:00:12]

Description was changed from

==========
Add missing histograms entry for GPU process startup time.

Added way back in http://crrev.com/131691, but never had an XML
entry added so it would show up on the dashboard!

This means the UMA was logged (I think), but is not visible on
dashboards. Found while working on http://crrev.com/1805163002

BUG=none
TEST=none
==========

to

==========
Add missing histograms entry for GPU process startup time.

Added way back in http://crrev.com/131691, but never had an XML
entry added so it would show up on the dashboard!

This means the UMA was logged (I think), but is not visible on
dashboards. Found while working on http://crrev.com/1805163002

BUG=none
TEST=none

Committed: https://crrev.com/4d29aa7b57b7297baabb45524ee205d4d35d4e35
Cr-Commit-Position: refs/heads/master@{#382104}
==========

[commit-bot: I haz the power, 2016-03-18 22:00:13]

Patchset 2 (id:??) landed as
https://crrev.com/4d29aa7b57b7297baabb45524ee205d4d35d4e35
Cr-Commit-Position: refs/heads/master@{#382104}