Revert 57254 - Share one thread between all AudioOutputControllers instead of...

media/audio/mac/audio_manager_mac.cc

Index: media/audio/mac/audio_manager_mac.cc
===================================================================
--- media/audio/mac/audio_manager_mac.cc	(revision 57255)
+++ media/audio/mac/audio_manager_mac.cc	(working copy)
@@ -4,6 +4,7 @@
 
 #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"
@@ -74,7 +75,22 @@
   delete stream;
 }
 
-// static
-AudioManager* AudioManager::CreateAudioManager() {
-  return new AudioManagerMac();
+namespace {
+
+AudioManagerMac* g_audio_manager = NULL;
+
+}  // namespace.
+
+void DestroyAudioManagerMac(void* param) {
+  delete g_audio_manager;
+  g_audio_manager = NULL;
 }
+
+// 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;
+}