Revert of Revert of Remove the last piece of deprecated synchronous IO code.

media/audio/alsa/audio_manager_alsa.cc

 // Copyright 2013 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/alsa/audio_manager_alsa.h"
 
 #include "base/command_line.h"
 #include "base/environment.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
@@ skipping 293 matching lines @@
 AudioParameters AudioManagerAlsa::GetPreferredOutputStreamParameters(
     const std::string& output_device_id,
     const AudioParameters& input_params) {
   // TODO(tommi): Support |output_device_id|.
   DLOG_IF(ERROR, !output_device_id.empty()) << "Not implemented!";
   static const int kDefaultOutputBufferSize = 2048;
   ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   int sample_rate = kDefaultSampleRate;
   int buffer_size = kDefaultOutputBufferSize;
   int bits_per_sample = 16;
-  int input_channels = 0;
   if (input_params.IsValid()) {
     // Some clients, such as WebRTC, have a more limited use case and work
     // acceptably with a smaller buffer size.  The check below allows clients
     // which want to try a smaller buffer size on Linux to do so.
     // TODO(dalecurtis): This should include bits per channel and channel layout
     // eventually.
     sample_rate = input_params.sample_rate();
     bits_per_sample = input_params.bits_per_sample();
     channel_layout = input_params.channel_layout();
-    input_channels = input_params.input_channels();
     buffer_size = std::min(input_params.frames_per_buffer(), buffer_size);
   }
 
   int user_buffer_size = GetUserBufferSize();
   if (user_buffer_size)
     buffer_size = user_buffer_size;
 
   return AudioParameters(
-      AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout, input_channels,
+      AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout,
       sample_rate, bits_per_sample, buffer_size, AudioParameters::NO_EFFECTS);
 }
 
 AudioOutputStream* AudioManagerAlsa::MakeOutputStream(
     const AudioParameters& params) {
   std::string device_name = AlsaPcmOutputStream::kAutoSelectDevice;
   if (CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kAlsaOutputDevice)) {
     device_name = CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
         switches::kAlsaOutputDevice);
   }
   return new AlsaPcmOutputStream(device_name, params, wrapper_.get(), this);
 }
 
 AudioInputStream* AudioManagerAlsa::MakeInputStream(
     const AudioParameters& params, const std::string& device_id) {
   std::string device_name = (device_id == AudioManagerBase::kDefaultDeviceId) ?
       AlsaPcmInputStream::kAutoSelectDevice : device_id;
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kAlsaInputDevice)) {
     device_name = CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
         switches::kAlsaInputDevice);
   }
 
   return new AlsaPcmInputStream(this, device_name, params, wrapper_.get());
 }
 
 }  // namespace media