Force layout to make a track rendering test non-flaky

Force layout to make a track rendering test non-flaky

While !textTracksAreReady(), readyState is constrained to
HAVE_CURRENT_DATA or lower. Once text tracks are ready, if the media
load has already progressed far, the canplaythrough event dispatch and
the text track rendering will be racy.

Since the rendering is not observable to Web content, it does not seem
worthwhile trying to make this deterministic.

The same fix was applied to WebKit:
http://trac.webkit.org/changeset/148050/trunk/LayoutTests/media/track/track-cue-container-rendering-position.html

BUG=330049
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181310

[philipj_slow, 2014-09-03 09:39:11]

philipj@opera.com changed reviewers:
+ acolwell@chromium.org, fs@opera.com

[philipj_slow, 2014-09-03 09:39:12]

PTAL

[fs, 2014-09-03 10:33:02]

lgtm

https://codereview.chromium.org/533073003/diff/1/LayoutTests/media/track/trac...
File LayoutTests/media/track/track-cue-container-rendering-position.html
(right):

https://codereview.chromium.org/533073003/diff/1/LayoutTests/media/track/trac...
LayoutTests/media/track/track-cue-container-rendering-position.html:24:
testExpected("cueDisplayElement.offsetTop > (video.videoHeight * .75)", true);
Any idea why reading cueDisplayElement.offsetTop is not sufficient?

[philipj_slow, 2014-09-03 11:31:55]

https://codereview.chromium.org/533073003/diff/1/LayoutTests/media/track/trac...
File LayoutTests/media/track/track-cue-container-rendering-position.html
(right):

https://codereview.chromium.org/533073003/diff/1/LayoutTests/media/track/trac...
LayoutTests/media/track/track-cue-container-rendering-position.html:24:
testExpected("cueDisplayElement.offsetTop > (video.videoHeight * .75)", true);
On 2014/09/03 10:33:02, fs wrote:
> Any idea why reading cueDisplayElement.offsetTop is not sufficient?

While debugging I replaced it with a constant and that passed consistently with
the forced layout. I'm guessing that font rendering differences will cause it to
be slightly different on different platforms, but didn't investigate further.

[philipj_slow, 2014-09-03 11:32:08]

The CQ bit was checked by philipj@opera.com

[commit-bot: I haz the power, 2014-09-03 11:33:04]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/philipj@opera.com/533073003/1

[commit-bot: I haz the power, 2014-09-03 12:20:48]

Committed patchset #1 (id:1) as 181310