[Chromecast] Remove command-line switch to change the number of mixer output channels

chromecast/media/cma/backend/alsa/stream_mixer_alsa.h

 // Copyright 2015 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.
 
 #ifndef CHROMECAST_MEDIA_CMA_BACKEND_ALSA_STREAM_MIXER_ALSA_H_
 #define CHROMECAST_MEDIA_CMA_BACKEND_ALSA_STREAM_MIXER_ALSA_H_
 
 #include <alsa/asoundlib.h>
 #include <stdint.h>
 
@@ skipping 102 matching lines @@
     kStateNormalPlayback,
     kStateError,
   };
 
   static StreamMixerAlsa* Get();
   static void MakeSingleThreadedForTest();
 
   int output_samples_per_second() const { return output_samples_per_second_; }
   bool empty() const { return inputs_.empty(); }
   State state() const { return state_; }
-  int num_output_channels() const { return num_output_channels_; }
 
   const scoped_refptr<base::SingleThreadTaskRunner>& task_runner() const {
     return mixer_task_runner_;
   }
 
   // Adds an input to the mixer. The input will live at least until
   // RemoveInput(input) is called. Can be called on any thread.
   void AddInput(std::unique_ptr<InputQueue> input);
   // Instructs the mixer to remove an input. The input should not be referenced
   // after this is called. Can be called on any thread.
@@ skipping 65 matching lines @@
   int requested_output_samples_per_second_;
   int output_samples_per_second_;
   snd_pcm_t* pcm_;
   snd_pcm_hw_params_t* pcm_hw_params_;
   snd_pcm_status_t* pcm_status_;
   snd_pcm_format_t pcm_format_;
 
   // User-configurable ALSA parameters. This caches the results, so the code
   // only has to interact with the command line parameters once.
   std::string alsa_device_name_;
-  int num_output_channels_;
   snd_pcm_uframes_t alsa_buffer_size_;
   bool alsa_period_explicitly_set;
   snd_pcm_uframes_t alsa_period_size_;
   snd_pcm_uframes_t alsa_start_threshold_;
   snd_pcm_uframes_t alsa_avail_min_;
 
   State state_;
 
   std::vector<std::unique_ptr<InputQueue>> inputs_;
   std::vector<std::unique_ptr<InputQueue>> ignored_inputs_;
@@ skipping 14 matching lines @@
 
   std::vector<CastMediaShlib::LoopbackAudioObserver*> loopback_observers_;
 
   DISALLOW_COPY_AND_ASSIGN(StreamMixerAlsa);
 };
 
 }  // namespace media
 }  // namespace chromecast
 
 #endif  // CHROMECAST_MEDIA_CMA_BACKEND_ALSA_STREAM_MIXER_ALSA_H_