Add thread safety to AudioManagerBase to protect access to the audio thread member variable.

Add thread safety to AudioManagerBase to protect access to the audio thread member variable.
This is is a tentative fix for an issue where the AudioManager can crash while tearing down
the audio thread. I suspect that this happens because more than one cleanup attempts were
made since the class wasn't thread safe. I'm also changing direct access to the thread's
MessageLoop* to use MessageLoopProxy based on the same theory.

BUG=110051
TEST=Run media tests.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=118272

[enal1, 2012-01-18 18:03:17]

LGTM.

I hope you fix the trybot failures.

[scherkus (not reviewing), 2012-01-18 18:12:31]

drive by

https://chromiumcodereview.appspot.com/9255017/diff/1/media/audio/audio_manag...
File media/audio/audio_manager_base.cc (right):

https://chromiumcodereview.appspot.com/9255017/diff/1/media/audio/audio_manag...
media/audio/audio_manager_base.cc:110: return;
indent

https://chromiumcodereview.appspot.com/9255017/diff/1/media/audio/audio_outpu...
File media/audio/audio_output_dispatcher.cc (right):

https://chromiumcodereview.appspot.com/9255017/diff/1/media/audio/audio_outpu...
media/audio/audio_output_dispatcher.cc:138: bool
AudioOutputDispatcher::CurrentThreadIsAudioThread() const {
nit: if this is a single threaded/non-thread safe object the alternative is to
inherit from NonThreadSafe and use CalledOnValidThread()

[tommi (sloooow) - chröme, 2012-01-18 19:59:39]

Thanks Andrew.  That's a good suggestion. I'll make the change and ping
back once everything is green and done.
Btw, I'll need to add some files from the content/ folder - is it OK to add
you as reviewer (need owner)?

On Wed, Jan 18, 2012 at 7:12 PM, <scherkus@chromium.org> wrote:

> drive by
>
>
> https://chromiumcodereview.**appspot.com/9255017/diff/1/**
>
media/audio/audio_manager_**base.cc<https://chromiumcodereview.appspot.com/9255017/diff/1/media/audio/audio_manager_base.cc>
> File media/audio/audio_manager_**base.cc (right):
>
> https://chromiumcodereview.**appspot.com/9255017/diff/1/**
>
media/audio/audio_manager_**base.cc#newcode110<https://chromiumcodereview.appspot.com/9255017/diff/1/media/audio/audio_manager_base.cc#newcode110>
> media/audio/audio_manager_**base.cc:110: return;
> indent
>
> https://chromiumcodereview.**appspot.com/9255017/diff/1/**
>
media/audio/audio_output_**dispatcher.cc<https://chromiumcodereview.appspot.com/9255017/diff/1/media/audio/audio_output_dispatcher.cc>
> File media/audio/audio_output_**dispatcher.cc (right):
>
> https://chromiumcodereview.**appspot.com/9255017/diff/1/**
>
media/audio/audio_output_**dispatcher.cc#newcode138<https://chromiumcodereview.appspot.com/9255017/diff/1/media/audio/audio_output_dispatcher.cc#newcode138>
> media/audio/audio_output_**dispatcher.cc:138: bool
> AudioOutputDispatcher::**CurrentThreadIsAudioThread() const {
> nit: if this is a single threaded/non-thread safe object the alternative
> is to inherit from NonThreadSafe and use CalledOnValidThread()
>
>
https://chromiumcodereview.**appspot.com/9255017/<https://chromiumcodereview....
>

[tommi (sloooow) - chröme, 2012-01-18 20:00:32]

Thanks Eugene - yes... failed to include files from content :-/ sorry about
that. Will fix tonight.

On Wed, Jan 18, 2012 at 7:03 PM, <enal@google.com> wrote:

> LGTM.
>
> I hope you fix the trybot failures.
>
>
https://chromiumcodereview.**appspot.com/9255017/<https://chromiumcodereview....
>

[tommi (sloooow) - chröme, 2012-01-18 23:09:07]

ok, all done.

[scherkus (not reviewing), 2012-01-19 01:39:59]

thanks!!

LGTM w/ one nit

https://chromiumcodereview.appspot.com/9255017/diff/3003/media/audio/audio_ou...
File media/audio/audio_output_proxy.h (right):

https://chromiumcodereview.appspot.com/9255017/diff/3003/media/audio/audio_ou...
media/audio/audio_output_proxy.h:25: class MEDIA_EXPORT AudioOutputProxy :
nit: initializer list format

class Foo
    : public Bar,
      public Baz, {
  // ....
};