When allocation rate is low and we are close to the new space limit, we should perform a scavenge d…

When allocation rate is low and we are close to the new space limit, we should perform a scavenge during idle time.

BUG=chromium:517395
LOG=n

Committed: https://crrev.com/9df592c1c5fe43746b567c36212d343427f09f39
Cr-Commit-Position: refs/heads/master@{#30044}

[Hannes Payer (out of office), 2015-08-06 11:36:16]

hpayer@chromium.org changed reviewers:
+ ulan@chromium.org

[ulan, 2015-08-06 11:49:35]

lgtm

[Hannes Payer (out of office), 2015-08-06 11:52:44]

The CQ bit was checked by hpayer@chromium.org

[commit-bot: I haz the power, 2015-08-06 11:52:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1272573006/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1272573006/20001

[commit-bot: I haz the power, 2015-08-06 12:10:30]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-06 12:10:50]

Patchset 2 (id:??) landed as
https://crrev.com/9df592c1c5fe43746b567c36212d343427f09f39
Cr-Commit-Position: refs/heads/master@{#30044}