Adds COM init to AudioManager thread for Windows

media/audio/win/audio_low_latency_output_win.h

 // Copyright (c) 2012 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.
 //
 // Implementation of AudioOutputStream for Windows using Windows Core Audio
 // WASAPI for low latency rendering.
 //
 // Overview of operation and performance:
 //
 // - An object of WASAPIAudioOutputStream is created by the AudioManager
@@ skipping 72 matching lines @@
 // - Support for 8-bit audio has not yet been verified and tested.
 // - Open() will fail if channel up-mixing is done for 8-bit audio.
 // - Supported channel up-mixing cases (client config -> endpoint config):
 //    o 1 -> 2
 //    o 1 -> 7.1
 //    o 2 -> 5.1
 //    o 2 -> 7.1
 //
 // Core Audio API details:
 //
-// - CoInitializeEx() is called on the creating thread and on the internal
-//   capture thread. Each thread's concurrency model and apartment is set
-//   to multi-threaded (MTA). CHECK() is called to ensure that we crash if
-//   CoInitializeEx(MTA) fails.
 // - The public API methods (Open(), Start(), Stop() and Close()) must be
 //   called on constructing thread. The reason is that we want to ensure that
 //   the COM environment is the same for all API implementations.
 // - Utilized MMDevice interfaces:
 //     o IMMDeviceEnumerator
 //     o IMMDevice
 // - Utilized WASAPI interfaces:
 //     o IAudioClient
 //     o IAudioRenderClient
 // - The stream is initialized in shared mode and the processing of the
@@ skipping 181 matching lines @@
   // processing/mixing of shared-mode streams for the default endpoint device.
   int endpoint_channel_count() { return format_.Format.nChannels; }
 
   // The ratio between the the number of native audio channels used by the
   // audio device and the number of audio channels from the client.
   double channel_factor() const {
     return (format_.Format.nChannels / static_cast<double> (
         client_channel_count_));
   }
 
-  // Initializes the COM library for use by the calling thread and sets the
-  // thread's concurrency model to multi-threaded.
-  base::win::ScopedCOMInitializer com_init_;
-
   // Contains the thread ID of the creating thread.
   base::PlatformThreadId creating_thread_id_;
 
   // Our creator, the audio manager needs to be notified when we close.
   AudioManagerWin* manager_;
 
   // Rendering is driven by this thread (which has no message loop).
   // All OnMoreData() callbacks will be called from this thread.
   scoped_ptr<base::DelegateSimpleThread> render_thread_;
 
@@ skipping 81 matching lines @@
 
   // Container for retrieving data from AudioSourceCallback::OnMoreData().
   scoped_ptr<AudioBus> audio_bus_;
 
   DISALLOW_COPY_AND_ASSIGN(WASAPIAudioOutputStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_WIN_AUDIO_LOW_LATENCY_OUTPUT_WIN_H_