Fix safepoint entering when waiting for a debugger task.

Fix safepoint entering when waiting for a debugger task.

When attempting to run worker debugger tasks, a timed wait is made on
the underlying task queue. While doing so, we are at a safepoint wrt
Blink GCs for the worker, and enter a safepoint scope.

The worker thread's stack will not be empty and clear of potential heap
references at that point; enter the safepoint with an appropriate
stack state.

R=
BUG=582710
Committed: https://crrev.com/137b56ddd5a272f4556ea2ff01bc7eba25866f5d
Cr-Commit-Position: refs/heads/master@{#372570}

[sof, 2016-01-30 19:56:10]

The CQ bit was checked by sigbjornf@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2016-01-30 19:56:20]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1656533002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1656533002/1

[commit-bot: I haz the power, 2016-01-30 21:08:24]

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

[commit-bot: I haz the power, 2016-01-30 21:08:24]

Dry run: This issue passed the CQ dry run.

[sof, 2016-01-30 21:28:12]

sigbjornf@opera.com changed reviewers:
+ oilpan-reviews@chromium.org

[sof, 2016-01-30 21:28:13]

please take a look.

Oversight as part of moving away from WorkerRunLoop in
https://codereview.chromium.org/423303004/

[haraken, 2016-01-31 04:37:43]

LGTM

[haraken, 2016-01-31 04:37:47]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2016-01-31 04:37:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1656533002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1656533002/1

[commit-bot: I haz the power, 2016-01-31 04:41:59]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-01-31 04:42:54]

Description was changed from

==========
Fix safepoint entering when waiting for a debugger task.

When attempting to run worker debugger tasks, a timed wait is made on
the underlying task queue. While doing so, we are at a safepoint wrt
Blink GCs for the worker, and enter a safepoint scope.

The worker thread's stack will not be empty and clear of potential heap
references at that point; enter the safepoint with an appropriate
stack state.

R=
BUG=582710
==========

to

==========
Fix safepoint entering when waiting for a debugger task.

When attempting to run worker debugger tasks, a timed wait is made on
the underlying task queue. While doing so, we are at a safepoint wrt
Blink GCs for the worker, and enter a safepoint scope.

The worker thread's stack will not be empty and clear of potential heap
references at that point; enter the safepoint with an appropriate
stack state.

R=
BUG=582710

Committed: https://crrev.com/137b56ddd5a272f4556ea2ff01bc7eba25866f5d
Cr-Commit-Position: refs/heads/master@{#372570}
==========

[commit-bot: I haz the power, 2016-01-31 04:42:55]

Patchset 1 (id:??) landed as
https://crrev.com/137b56ddd5a272f4556ea2ff01bc7eba25866f5d
Cr-Commit-Position: refs/heads/master@{#372570}