Remove the AudioManager singleton.

media/audio/win/audio_manager_win.cc

 // Copyright (c) 2011 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 "media/audio/audio_io.h"
 
 #include <windows.h>
 #include <objbase.h>  // This has to be before initguid.h
 #include <initguid.h>
 #include <mmsystem.h>
@@ skipping 286 matching lines @@
   // Always add default device parameters as first element.
   if (!device_names->empty()) {
     media::AudioDeviceName name;
     name.device_name = AudioManagerBase::kDefaultDeviceName;
     name.unique_id = AudioManagerBase::kDefaultDeviceId;
     device_names->push_front(name);
   }
 }
 
 /// static
-AudioManager* AudioManager::CreateAudioManager() {
+AudioManager* CreateAudioManager() {
   return new AudioManagerWin();
 }