ProfileErrorBrowserTest should wait for layout.

ProfileErrorBrowserTest should wait for layout.

The test was checking for the Startup.FirstWebContents.NonEmptyPaint
histogram metric which is recorded by the didFirstVisuallyNonEmptyLayout
client callback out of blink. The test doesn't actually wait until after
the page does a layout though so it'll randomly fail when it loses the
race. Currently blink issues this callback too early when loading pages,
but soon (https://codereview.chromium.org/1295053002) it will start
only issuing the callback after stylesheets have loaded and the page
has started painting matching the usage in Chromium where this callback
maps to painting, not to layout.

To fix the race we now wait for requestAnimationFrame to run which will
ensure that the blink pipeline has been run, and layout and paint
processed before testing for the values of the UMA metrics.

BUG=521692
Committed: https://crrev.com/0ea17fce0d5218c909985e2216051eab79419463
Cr-Commit-Position: refs/heads/master@{#343796}

[esprehn, 2015-08-17 22:57:52]

esprehn@chromium.org changed reviewers:
+ gab@chromium.org, msw@chromium.org, thakis@chromium.org

[esprehn, 2015-08-17 23:11:16]

The CQ bit was checked by esprehn@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-17 23:11:58]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1284383007/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1284383007/1

[Nico, 2015-08-17 23:43:49]

thakis@chromium.org changed reviewers:
+ tiany@google.com

[Nico, 2015-08-17 23:43:49]

lgtm

Looks like the author of this test might no longer be with us, but this make
sense to me. Thanks for tracking this down!

[msw, 2015-08-17 23:45:35]

lgtm

[esprehn, 2015-08-18 00:01:12]

The CQ bit was unchecked by esprehn@chromium.org

[esprehn, 2015-08-18 00:01:13]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2015-08-18 00:02:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1284383007/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1284383007/1

[gab, 2015-08-18 01:38:40]

lgtm, thanks

[commit-bot: I haz the power, 2015-08-18 01:41:55]

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

[commit-bot: I haz the power, 2015-08-18 01:41:56]

Try jobs failed on following builders:
  linux_chromium_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[esprehn, 2015-08-18 03:43:09]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2015-08-18 03:43:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1284383007/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1284383007/1

[commit-bot: I haz the power, 2015-08-18 05:06:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-18 05:07:53]

Patchset 1 (id:??) landed as
https://crrev.com/0ea17fce0d5218c909985e2216051eab79419463
Cr-Commit-Position: refs/heads/master@{#343796}