Re-land r207105 (Mac audio capture threading fix) with unit test memory leak issue resolved.

Re-land r207105 (Mac audio capture threading fix) with unit test memory leak issue resolved.

Last attempt: https://codereview.chromium.org/17122006/

BUG=249089
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=208033

[miu, 2013-06-21 22:51:24]

Dale,

Patch Set 1 is the original change (plus rebase).

Patch Set 2 is where I added use of a DestructionObserver to resolve the unit
test memory leak issue.  However, IMHO, I don't think this is what we want:

1. This code seems overly complex at this point.  Too many LOC seem dedicated to
memory management.

2. There's a subtle race condition I don't see how to avoid between the
DeleteSoon() and WillDestroyCurrentMessageLoop() methods: It's possible for a
double delete to occur in the case where one thread is in DeleteSoon() at the
same time the MessageLoopProxy's DestructionObserver is called (followed by
Worker::WillDestroyCurrentMessageLoop()).

MY RECOMMENDATION: I think the ref-counting scheme
(https://codereview.chromium.org/17122006/#ps20001) is the simplest, cleanest
way to handle the memory management of FAC::Worker.  Furthermore, going this
route will completely resolve the memory leak issue since destruction of the
worker loop will automatically drop all references to FAC::Worker in a
thread-safe manner.

WDYT?

[miu, 2013-06-21 23:23:40]

Uploaded the patch that uses ref-counting.  PTAL.

[DaleCurtis, 2013-06-21 23:26:59]

lgtm

[commit-bot: I haz the power, 2013-06-21 23:32:09]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/miu@chromium.org/17334005/11001

[commit-bot: I haz the power, 2013-06-22 01:39:55]

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

[commit-bot: I haz the power, 2013-06-22 01:45:23]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/miu@chromium.org/17334005/11001

[commit-bot: I haz the power, 2013-06-22 02:39:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/miu@chromium.org/17334005/11001

[commit-bot: I haz the power, 2013-06-22 03:25:25]

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

[commit-bot: I haz the power, 2013-06-22 08:15:48]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/miu@chromium.org/17334005/11001

[commit-bot: I haz the power, 2013-06-22 14:18:30]

Change committed as 208033