Use the worker task runner instead of the main audio thread.

Use the worker task runner instead of the main audio thread.

On OSX the main audio thread is the UI thread due to limitations
in the CoreAudio API. Since we're making effectively read only
calls sending the audio hardware config from the worker task
runner should be fine. We already do this in several other places
for device enumeration (since it's way to slow on UI thread).

BUG=469737
TEST=none

Committed: https://crrev.com/06def69114b5ecae4f0ee0aa875181568fe7902c
Cr-Commit-Position: refs/heads/master@{#322292}

[DaleCurtis, 2015-03-24 20:44:56]

dalecurtis@chromium.org changed reviewers:
+ nasko@chromium.org

[nasko, 2015-03-24 23:33:05]

LGTM

[DaleCurtis, 2015-03-24 23:35:47]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2015-03-24 23:36:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1029933003/1

[commit-bot: I haz the power, 2015-03-25 02:45:40]

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

[commit-bot: I haz the power, 2015-03-25 02:45:41]

Try jobs failed on following builders:
  linux_chromium_chromeos_ozone_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[DaleCurtis, 2015-03-25 17:34:22]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2015-03-25 17:34:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1029933003/1

[DaleCurtis, 2015-03-25 22:32:12]

Whoops, had the wrong thread check after changing the loop posted to. Fixed.

[DaleCurtis, 2015-03-25 22:32:23]

The CQ bit was checked by dalecurtis@chromium.org

[DaleCurtis, 2015-03-25 22:32:24]

The patchset sent to the CQ was uploaded after l-g-t-m from nasko@chromium.org
Link to the patchset: https://codereview.chromium.org/1029933003/#ps20001
(title: "Fix thread check.")

[commit-bot: I haz the power, 2015-03-25 22:33:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1029933003/20001

[commit-bot: I haz the power, 2015-03-26 01:33:42]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-03-26 01:34:25]

Patchset 2 (id:??) landed as
https://crrev.com/06def69114b5ecae4f0ee0aa875181568fe7902c
Cr-Commit-Position: refs/heads/master@{#322292}