cc: Support mask layers in impl-side painting

cc: Support mask layers in impl-side painting

Mask layers just set always update their tiling to be exactly the size of the
mask content bounds, so that there's exactly one tile.

R=nduca@chromium.org
BUG=165730
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=174443

[enne (OOO), 2012-12-20 22:09:30]

Writing this patch makes me wonder if maybe we need a better mechanism than
didUpdateTransforms to kick off tile priority updates.  That function right now
gets called in calcDraw on layers that don't get skipped.

However, it seems like we want to call that even on layers that aren't going to
get drawn (in case they were previously drawn and need to update their tile
priorities to say that they're less important).  I don't want to add yet another
tree walk, but...

[nduca, 2012-12-21 01:51:20]

LGTM and maybe we should file a followup about how to do didUpdateTransforms
robustly?

[commit-bot: I haz the power, 2012-12-21 17:24:29]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/enne@chromium.org/11639050/1

[commit-bot: I haz the power, 2012-12-21 20:24:35]

Change committed as 174443