Change the way we are stopping audio stream on Mac once again.

Change the way we are stopping audio stream on Mac once again.

r142235 was not enough, we were not touching audio buffers after stop,
but OS could still touch audio queue. That causes problems if we were
deleting audio stream immediately after stopping, e.g. if audio mixer
tried to keep audio stream opened after last logical stream stopped
and then stopped/closed it.

I was able to reproduce the problem locally (for whatever reason this time
it worked), and after the fix it (finally) went away -- browsert_tests
PPAPITest.Audio_Creation successfully runs for 300 iterations. When I revert
to previos way of signaling, problem resurfaces again.

Fix is to use "property listener" to listen to "is running" audio queue
property, and signal "stream stopped" event only after "is running" property
changes to false. Functions that do are documented in the Apple core audio
documentation but not used in samples, so they are hard to find if you don't
know what to look for.
 
Also re-enabling mixer change to keep physical stream opened for some time,
That should complete browser-side mixer work and fix several related bugs.

BUG=102395
BUG=114701
BUG=129190
BUG=131720
TEST=No observable diffs, but crashes and seek problems should go away.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=142862

[scherkus (not reviewing), 2012-06-18 19:40:53]

https://chromiumcodereview.appspot.com/10560038/diff/1/media/audio/mac/audio_...
File media/audio/mac/audio_output_mac.cc (right):

https://chromiumcodereview.appspot.com/10560038/diff/1/media/audio/mac/audio_...
media/audio/mac/audio_output_mac.cc:435: audio_stream->stop_requested_ = true;
do we need to reset this to false at some point in time?

https://chromiumcodereview.appspot.com/10560038/diff/1/media/audio/mac/audio_...
media/audio/mac/audio_output_mac.cc:441: queue,
minor nit: in line 448 you use audio_stream->audio_queue -- double checking but
are these the same objects?

if so can you be consistent with which variable you use?

[enal1, 2012-06-18 19:58:47]

Replied.

As I changed the sources I am again building and running tests, it will take
some time. Will not check in before re-running tests.

https://chromiumcodereview.appspot.com/10560038/diff/1/media/audio/mac/audio_...
File media/audio/mac/audio_output_mac.cc (right):

https://chromiumcodereview.appspot.com/10560038/diff/1/media/audio/mac/audio_...
media/audio/mac/audio_output_mac.cc:435: audio_stream->stop_requested_ = true;
On 2012/06/18 19:40:53, scherkus wrote:
> do we need to reset this to false at some point in time?

When starting the stream. in PCMQueueOutAudioOutputStream::Start().

https://chromiumcodereview.appspot.com/10560038/diff/1/media/audio/mac/audio_...
media/audio/mac/audio_output_mac.cc:441: queue,
On 2012/06/18 19:40:53, scherkus wrote:
> minor nit: in line 448 you use audio_stream->audio_queue -- double checking
but
> are these the same objects?
> 
> if so can you be consistent with which variable you use?

Done.

[scherkus (not reviewing), 2012-06-18 20:07:35]

LGTM code-wise -- as you mention I'll leave it up to your for proper testing +
committing

nice fix!

[commit-bot: I haz the power, 2012-06-18 21:54:16]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/enal@chromium.org/10560038/5001

[commit-bot: I haz the power, 2012-06-18 23:42:54]

Change committed as 142862