Oilpan: Replace Heap::collectGarbage(...) with a helper function

Oilpan: Replace Heap::collectGarbage(...) with a helper function

The parameters are too verbose to write every time.

BUG=

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201045

[haraken, 2015-07-14 08:57:01]

haraken@chromium.org changed reviewers:
+ keishi@chromium.org

[haraken, 2015-07-14 08:57:01]

PTAL

[keishi, 2015-07-14 09:11:28]

lgtm

[haraken, 2015-07-14 12:37:51]

The CQ bit was checked by haraken@chromium.org

[haraken, 2015-07-14 12:37:52]

The patchset sent to the CQ was uploaded after l-g-t-m from keishi@chromium.org
Link to the patchset: https://codereview.chromium.org/1236183002/#ps20001
(title: " ")

[commit-bot: I haz the power, 2015-07-14 12:38:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1236183002/20001

[commit-bot: I haz the power, 2015-07-14 13:13:14]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-07-14 13:13:14]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/7...)

[haraken, 2015-08-23 23:52:16]

The CQ bit was checked by haraken@chromium.org

[haraken, 2015-08-23 23:52:16]

The patchset sent to the CQ was uploaded after l-g-t-m from keishi@chromium.org
Link to the patchset: https://codereview.chromium.org/1236183002/#ps40001
(title: " ")

[commit-bot: I haz the power, 2015-08-23 23:52:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1236183002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1236183002/40001

[commit-bot: I haz the power, 2015-08-24 00:45:41]

Committed patchset #3 (id:40001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201045