Allow WebRTC tests that watch for black frames to be off by one.

Allow WebRTC tests that watch for black frames to be off by one.

This leaves some room for YUV conversion rounding errors.

BUG=91208
Committed: https://crrev.com/6cc2c20cc7ae7d7b7e72db77bddead6daa7a7b77
Cr-Commit-Position: refs/heads/master@{#296677}

[rileya (GONE FROM CHROMIUM), 2014-09-25 03:47:25]

rileya@chromium.org changed reviewers:
+ perkj@chromium.org, phoglund@chromium.org

[rileya (GONE FROM CHROMIUM), 2014-09-25 03:47:25]

I'm working on GPU YUV conversion for video->canvas copies.

Sadly, differences in GPU/platform/etc mean we sometimes get
off-by-ones/rounding errors on what should be a pure black frame, where we
instead convert to RGB of, say, (1,0,1). This loosens the tests to allow this.

We get the exact same rounding errors in the <video> element itself when
hardware composited, so while this loosens the test requirements, it actually
makes them more representative of what the <video> element is actually
displaying.

[perkj_chrome, 2014-09-25 06:39:26]

The CQ bit was checked by perkj@chromium.org

[perkj_chrome, 2014-09-25 06:39:27]

lgtm

lgtm

[commit-bot: I haz the power, 2014-09-25 06:40:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/601083002/1

[commit-bot: I haz the power, 2014-09-25 07:39:05]

Committed patchset #1 (id:1) as 86589ddc34f699c51855dfbc3c9dc096f62b2c66

[commit-bot: I haz the power, 2014-09-25 07:39:38]

Patchset 1 (id:??) landed as
https://crrev.com/6cc2c20cc7ae7d7b7e72db77bddead6daa7a7b77
Cr-Commit-Position: refs/heads/master@{#296677}

[phoglund_chromium, 2014-09-25 09:45:10]

lgtm