cc: Fix masks when the RenderPassDrawQuad does not cover the whole pass

cc: Fix masks when the RenderPassDrawQuad does not cover the whole pass

If the RenderPassDrawQuad is not the same size as the texture backing
the RenderPass, then we have to scale the texture coordinates when
reading the pass texture.

If the pass has a mask as well, we have to scale those coordinates as
well. However the coordinates given to the mask shader are already
scaled to the size of the contents texture. We further scale and
offset the coordinates but the offset was incorrect.

Tested by:
RendererPixelTest.RenderPassAndMaskWithPartialQuad
LayerTreeHostMasksPixelTest.MaskOfClippedLayer

R=enne
BUG=264534
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=228376

[enne (OOO), 2013-10-11 21:36:01]

lgtm

Thanks for the pixel test!

[commit-bot: I haz the power, 2013-10-11 21:41:43]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/27040003/5001

[commit-bot: I haz the power, 2013-10-12 02:38:38]

Step "update" is always a major failure.
Look at the try server FAQ for more details.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2013-10-12 15:09:31]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/27040003/5001

[commit-bot: I haz the power, 2013-10-12 19:51:48]

Change committed as 228376