Record UMA for parser blocking time for scripts inserted via doc.write

Record UMA for parser blocking time for scripts inserted via doc.write.
This is an important metric for Project NeverIdle:
https://docs.google.com/document/d/1vUqy6uke6U1nalT6qlHbzl1LaXPHn9fLSXxGgUbMAxA/edit

BUG=588724
Committed: https://crrev.com/6b1149d34b4e5ccd19f033c246d6573f34e8c74e
Cr-Commit-Position: refs/heads/master@{#385863}

[Bryan McQuade, 2016-04-04 21:03:47]

Description was changed from

==========
Record UMA for parser blocking time for scripts inserted via doc.write

BUG=588724
==========

to

==========
Record UMA for parser blocking time for scripts inserted via doc.write.
This is an important metric for Project NeverIdle:
https://docs.google.com/document/d/1vUqy6uke6U1nalT6qlHbzl1LaXPHn9fLSXxGgUbMA...

BUG=588724
==========

[Bryan McQuade, 2016-04-05 15:54:57]

bmcquade@chromium.org changed reviewers:
+ asvitkine@chromium.org, csharrison@chromium.org

[Bryan McQuade, 2016-04-05 15:57:09]

csharrison, PTAL for page_load_metrics
asvitkine, PTAL for histograms.xml

Thanks!

[Alexei Svitkine (slow), 2016-04-05 21:22:42]

lgtm

[Charlie Harrison, 2016-04-06 12:37:51]

lgtm

[Bryan McQuade, 2016-04-07 20:31:45]

The CQ bit was checked by bmcquade@chromium.org

[Bryan McQuade, 2016-04-07 20:31:46]

The patchset sent to the CQ was uploaded after l-g-t-m from
asvitkine@chromium.org, csharrison@chromium.org
Link to the patchset: https://codereview.chromium.org/1855413002/#ps80001
(title: "rebase")

[commit-bot: I haz the power, 2016-04-07 20:32:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1855413002/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1855413002/80001

[commit-bot: I haz the power, 2016-04-07 21:22:38]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2016-04-07 21:29:55]

Description was changed from

==========
Record UMA for parser blocking time for scripts inserted via doc.write.
This is an important metric for Project NeverIdle:
https://docs.google.com/document/d/1vUqy6uke6U1nalT6qlHbzl1LaXPHn9fLSXxGgUbMA...

BUG=588724
==========

to

==========
Record UMA for parser blocking time for scripts inserted via doc.write.
This is an important metric for Project NeverIdle:
https://docs.google.com/document/d/1vUqy6uke6U1nalT6qlHbzl1LaXPHn9fLSXxGgUbMA...

BUG=588724

Committed: https://crrev.com/6b1149d34b4e5ccd19f033c246d6573f34e8c74e
Cr-Commit-Position: refs/heads/master@{#385863}
==========

[commit-bot: I haz the power, 2016-04-07 21:29:56]

Patchset 5 (id:??) landed as
https://crrev.com/6b1149d34b4e5ccd19f033c246d6573f34e8c74e
Cr-Commit-Position: refs/heads/master@{#385863}