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

media/audio/win/audio_manager_win.cc

Index: media/audio/win/audio_manager_win.cc
diff --git a/media/audio/win/audio_manager_win.cc b/media/audio/win/audio_manager_win.cc
index 061d2d8458557c8c9b183781fd6790eb98033fcd..6c4a606cd4d54de00052d62e8bf586354ea18c11 100644
--- a/media/audio/win/audio_manager_win.cc
+++ b/media/audio/win/audio_manager_win.cc
@@ -7,7 +7,6 @@
 #include <windows.h>
 #include <mmsystem.h>
 
-#include "base/at_exit.h"
 #include "base/basictypes.h"
 #include "media/audio/fake_audio_input_stream.h"
 #include "media/audio/fake_audio_output_stream.h"
@@ -42,8 +41,6 @@ const int kMaxSamplesPerPacket = kMaxSampleRate;
 // play.
 const int kNumInputBuffers = 3;
 
-AudioManagerWin* g_audio_manager = NULL;
-
 }  // namespace.
 
 bool AudioManagerWin::HasAudioOutputDevices() {
@@ -125,15 +122,7 @@ void AudioManagerWin::UnMuteAll() {
 AudioManagerWin::~AudioManagerWin() {
 }
 
-void DestroyAudioManagerWin(void* param) {
-  delete g_audio_manager;
-  g_audio_manager = NULL;
-}
-
-AudioManager* AudioManager::GetAudioManager() {
-  if (!g_audio_manager) {
-    g_audio_manager = new AudioManagerWin();
-    base::AtExitManager::RegisterCallback(&DestroyAudioManagerWin, NULL);
-  }
-  return g_audio_manager;
+// static
+AudioManager* AudioManager::CreateAudioManager() {
+  return new AudioManagerWin();
 }