[cc] Fix zebra-stripe compositor checkerboarding

[cc] Fix zebra-stripe compositor checkerboarding

It seems likely that medium precision floating point uniforms on some hardware
are running out of precision.  Fix in the short term by doing an int mod of the
texture coordinate prior to setting the uniform.

BUG=150829
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=160030

[enne (OOO), 2012-10-03 22:35:26]

I couldn't repro this on desktop, but this seems super likely to be the problem
on ChromeOS.  It's also safe to do and I verified that checkerboards still look
fine on Desktop.

[jamesr, 2012-10-03 22:42:49]

lgtm. I'll try this out on a snow

[commit-bot: I haz the power, 2012-10-03 22:46:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/enne@chromium.org/11051029/1

[jamesr, 2012-10-03 22:52:21]

On 2012/10/03 22:42:49, jamesr wrote:
> lgtm. I'll try this out on a snow

Seems to work

[commit-bot: I haz the power, 2012-10-04 01:01:57]

Change committed as 160030

[marcheu, 2012-10-04 01:08:41]

Could we try on pineview? We don't have integers (they're not part of GL 2.0
which is our requirement).

[marcheu, 2012-10-04 01:09:19]

Ah nevermind it's not shader code :)