Adds COM init to AudioManager thread for Windows

media/audio/audio_manager_base.cc

Index: media/audio/audio_manager_base.cc
diff --git a/media/audio/audio_manager_base.cc b/media/audio/audio_manager_base.cc
index 435cf9ee8c677ac4aa09f9f4490d40e366e75904..edc8bb41f71a8c09492fae668a82140e598be8d7 100644
--- a/media/audio/audio_manager_base.cc
+++ b/media/audio/audio_manager_base.cc
@@ -8,6 +8,7 @@
 #include "base/command_line.h"
 #include "base/message_loop_proxy.h"
 #include "base/threading/thread.h"
+#include "base/win/scoped_com_initializer.h"
 #include "media/audio/audio_output_dispatcher_impl.h"
 #include "media/audio/audio_output_proxy.h"
 #include "media/audio/audio_output_resampler.h"
@@ -39,6 +40,40 @@ static const int kMaxInputChannels = 2;
 const char AudioManagerBase::kDefaultDeviceName[] = "Default";
 const char AudioManagerBase::kDefaultDeviceId[] = "default";
 
+// Initializes the COM library for use by this thread and sets the thread's
+// COM threading model on Windows to MTA.
+class AudioThread : public base::Thread {
+public:

[scherkus (not reviewing), 2012/09/17 16:50:04]

indent one space

[henrika (OOO until Aug 14), 2012/09/17 17:00:50]

Done.

+  AudioThread();
+  virtual ~AudioThread();
+
+protected:

[scherkus (not reviewing), 2012/09/17 16:50:04]

indent one space

[henrika (OOO until Aug 14), 2012/09/17 17:00:50]

Done.

+  virtual void Init() OVERRIDE;
+  virtual void CleanUp() OVERRIDE;
+
+private:

[scherkus (not reviewing), 2012/09/17 16:50:04]

indent one space

[henrika (OOO until Aug 14), 2012/09/17 17:00:50]

Done.

+  scoped_ptr<base::win::ScopedCOMInitializer> com_initializer_;

[scherkus (not reviewing), 2012/09/17 16:50:04]

q: this has to be a scoped_ptr<> because we need to CoUninit() in CleanUp() as
opposed to ~AudioThread()?

[henrika (OOO until Aug 14), 2012/09/17 17:00:50]

Good question. I base it on a similar design in the media stream manager (done
by Shijing, reviewed by Tommi) where this was tried without success. I honestly
don't know why exactly.

+  DISALLOW_COPY_AND_ASSIGN(AudioThread);
+};
+
+AudioThread::AudioThread()
+    : base::Thread("AudioThread") {

[scherkus (not reviewing), 2012/09/17 16:50:04]

nit: can fit on previous line

[henrika (OOO until Aug 14), 2012/09/17 17:00:50]

Done.

+}
+
+AudioThread::~AudioThread() {
+  Stop();
+}
+
+void AudioThread::Init() {
+  using base::win::ScopedCOMInitializer;

[scherkus (not reviewing), 2012/09/17 16:50:04]

nit: move this statement to before "namespace media" -- that way you can also
trim down the declaration inside scoped_ptr<T>

[henrika (OOO until Aug 14), 2012/09/17 17:00:50]

Cool. Thanks.

+  com_initializer_.reset(new ScopedCOMInitializer(ScopedCOMInitializer::kMTA));
+  CHECK(com_initializer_->succeeded());
+}
+
+void AudioThread::CleanUp() {
+  com_initializer_.reset();
+}
+
 AudioManagerBase::AudioManagerBase()
     : num_active_input_streams_(0),
       max_num_output_streams_(kDefaultMaxOutputStreams),
@@ -63,7 +98,7 @@ AudioManagerBase::~AudioManagerBase() {
 void AudioManagerBase::Init() {
   base::AutoLock lock(audio_thread_lock_);
   DCHECK(!audio_thread_.get());
-  audio_thread_.reset(new base::Thread("AudioThread"));
+  audio_thread_.reset(new media::AudioThread());
   CHECK(audio_thread_->Start());
 }
 
@@ -228,7 +263,7 @@ bool AudioManagerBase::IsRecordingInProcess() {
 void AudioManagerBase::Shutdown() {
   // To avoid running into deadlocks while we stop the thread, shut it down
   // via a local variable while not holding the audio thread lock.
-  scoped_ptr<base::Thread> audio_thread;
+  scoped_ptr<media::AudioThread> audio_thread;
   {
     base::AutoLock lock(audio_thread_lock_);
     audio_thread_.swap(audio_thread);