cc: Maximize pending updates.

cc: Maximize pending updates.

This makes the resource update controller maintain a maximum number of
pending updates. This keeps our pipeline better filled without
theoretically increasing the risk that we delay drawing at vsync tick.

BUG=145825
TEST=cc_unittests and manual testing


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=166298

[reveman, 2012-10-29 19:16:20]

This is a rebased and simplified version of Brian's
https://codereview.chromium.org/10963039/ change.

This reduces GPU process idle time significantly when performing texture uploads
and I think it's generally a better approach for scheduling resource updates.

[nduca, 2012-11-05 06:55:09]

Can we back this up with numbers?

[nduca, 2012-11-06 20:12:57]

lgtm

[commit-bot: I haz the power, 2012-11-06 21:29:16]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/reveman@chromium.org/11347019/4001

[commit-bot: I haz the power, 2012-11-06 23:26:52]

Change committed as 166298