Caching AudioOutputDevice instances in mixer manager

media/renderers/audio_renderer_impl.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.
 
 // Audio rendering unit utilizing an AudioRendererSink to output data.
 //
 // This class lives inside three threads during it's lifetime, namely:
 // 1. Render thread
 //    Where the object is created.
 // 2. Media thread (provided via constructor)
@@ skipping 46 matching lines @@
  public:
   // |task_runner| is the thread on which AudioRendererImpl will execute.
   //
   // |sink| is used as the destination for the rendered audio.
   //
   // |decoders| contains the AudioDecoders to use when initializing.
   AudioRendererImpl(
       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
       AudioRendererSink* sink,
       ScopedVector<AudioDecoder> decoders,
-      const AudioHardwareConfig& hardware_config,
       const scoped_refptr<MediaLog>& media_log);
   ~AudioRendererImpl() override;
 
   // TimeSource implementation.
   void StartTicking() override;
   void StopTicking() override;
   void SetPlaybackRate(double rate) override;
   void SetMediaTime(base::TimeDelta time) override;
   base::TimeDelta CurrentMediaTime() override;
   bool GetWallClockTimes(
@@ skipping 122 matching lines @@
   // Whether or not we expect to handle config changes.
   bool expecting_config_changes_;
 
   // The sink (destination) for rendered audio. |sink_| must only be accessed
   // on |task_runner_|. |sink_| must never be called under |lock_| or else we
   // may deadlock between |task_runner_| and the audio callback thread.
   scoped_refptr<media::AudioRendererSink> sink_;
 
   std::unique_ptr<AudioBufferStream> audio_buffer_stream_;
 
-  // Interface to the hardware audio params.
-  const AudioHardwareConfig& hardware_config_;
-
   scoped_refptr<MediaLog> media_log_;
 
-  // Cached copy of hardware params from |hardware_config_|.
+  // Cached copy of hardware params from |sink_|.
   AudioParameters audio_parameters_;
 
   // Callbacks provided during Initialize().
   PipelineStatusCB init_cb_;
   BufferingStateCB buffering_state_cb_;
   base::Closure ended_cb_;
   PipelineStatusCB error_cb_;
   StatisticsCB statistics_cb_;
 
   // Callback provided to Flush().
@@ skipping 66 matching lines @@
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<AudioRendererImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_RENDERERS_AUDIO_RENDERER_IMPL_H_