Remove use of CoreAudioUtil::IsSupported() from AudioManager startup.

Remove use of CoreAudioUtil::IsSupported() from AudioManager startup.

The method attempts to load the audioses.dll and create an
MMDeviceEnumerator object.  Such actions should be avoided in the
constructor since it's blocking the UI loop.

BUG=none
TEST=none

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=246527

[DaleCurtis, 2014-01-22 02:47:50]

Found while discussing potential sources of UI thread slowness.

[henrika (OOO until Aug 14), 2014-01-22 09:24:27]

Looks like a nice cleanup for many reasons. May I ask for some more details on
how you identified the issue?

LGTM

[DaleCurtis, 2014-01-22 18:32:59]

No actual issues that I know of, it's more a theoretical change to avoid as much
as we can on startup.

[commit-bot: I haz the power, 2014-01-22 18:33:29]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/144613003/30001

[commit-bot: I haz the power, 2014-01-22 19:41:04]

Retried try job too often on win_rel for step(s) content_unittests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2014-01-22 23:54:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/144613003/310001

[commit-bot: I haz the power, 2014-01-23 01:49:05]

Retried try job too often on linux_chromeos for step(s) interactive_ui_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_chro...

[commit-bot: I haz the power, 2014-01-23 01:52:31]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/144613003/310001

[commit-bot: I haz the power, 2014-01-23 04:35:57]

Change committed as 246527

[henrika (OOO until Aug 14), 2014-01-23 08:37:18]

Sounds great. I like it.