Share one thread between all AudioOutputControllers instead of creating one per stream.

media/audio/mac/audio_manager_mac.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <CoreAudio/AudioHardware.h>
 
-#include "base/at_exit.h"
 #include "media/audio/fake_audio_input_stream.h"
 #include "media/audio/fake_audio_output_stream.h"
 #include "media/audio/mac/audio_manager_mac.h"
 #include "media/audio/mac/audio_output_mac.h"
 
 bool AudioManagerMac::HasAudioOutputDevices() {
   AudioDeviceID output_device_id = kAudioObjectUnknown;
   AudioObjectPropertyAddress property_address = {
     kAudioHardwarePropertyDefaultOutputDevice,  // mSelector
     kAudioObjectPropertyScopeGlobal,            // mScope
@@ skipping 50 matching lines @@
 void AudioManagerMac::UnMuteAll() {
   // TODO(cpu): implement.
 }
 
 // Called by the stream when it has been released by calling Close().
 void AudioManagerMac::ReleaseOutputStream(
     PCMQueueOutAudioOutputStream* stream) {
   delete stream;
 }
 
-namespace {
-
-AudioManagerMac* g_audio_manager = NULL;
-
-}  // namespace.
-
-void DestroyAudioManagerMac(void* param) {
-  delete g_audio_manager;
-  g_audio_manager = NULL;
+// static
+AudioManager* AudioManager::CreateAudioManager() {
+  return new AudioManagerMac();
 }
-
-// By convention, the AudioManager is not thread safe.
-AudioManager* AudioManager::GetAudioManager() {
-  if (!g_audio_manager) {
-    g_audio_manager = new AudioManagerMac();
-    base::AtExitManager::RegisterCallback(&DestroyAudioManagerMac, NULL);
-  }
-  return g_audio_manager;
-}