cc: Check for cheap task completion sooner

cc: Check for cheap task completion sooner

Instead of using the normal 6 ms period to poll for cheap task
completion, do the check immediately after running a batch of cheap
tasks. This improves cheap task completion latency.

In order to avoid disturbing the scheduling of normal task completion,
this optimization is only performed if there are no pending non-cheap
tasks.

BUG=178441
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=185051

[Sami, 2013-02-26 17:50:37]

See https://code.google.com/p/chromium/issues/detail?id=178441 for some data
about this patch.

[reveman, 2013-02-26 20:43:09]

Are we just not missing a call to OnIdle? The worker pool is supposed to be
processing completed tasks as soon as it becomes idle and it seems like that's
just not working correctly.

[Sami, 2013-02-27 11:33:53]

On 2013/02/26 20:43:09, David Reveman wrote:
> Are we just not missing a call to OnIdle? The worker pool is supposed to be
> processing completed tasks as soon as it becomes idle and it seems like that's
> just not working correctly.

You're absolutely right. Calling OnIdle when there's nothing more to do makes
much more sense.

[reveman, 2013-02-27 18:21:05]

lgtm

[commit-bot: I haz the power, 2013-02-27 18:29:41]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/skyostil@chromium.org/12321140/3

[commit-bot: I haz the power, 2013-02-27 22:02:21]

Change committed as 185051