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

components/copresence/mediums/audio/audio_recorder_unittest.cc

 // Copyright 2014 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 "components/copresence/mediums/audio/audio_recorder.h"
 
 #include "base/bind.h"
 #include "base/memory/aligned_memory.h"
 #include "base/run_loop.h"
 #include "components/copresence/public/copresence_constants.h"
@@ skipping 79 matching lines @@
   }
 
   void CreateRecorder(size_t channels,
                       size_t sample_rate,
                       size_t bits_per_sample,
                       size_t samples) {
     DeleteRecorder();
     params_.Reset(media::AudioParameters::AUDIO_PCM_LOW_LATENCY,
                   kDefaultChannelLayout,
                   channels,
-                  2,
                   sample_rate,
                   bits_per_sample,
                   4096);
 
     channel_data_.clear();
     channel_data_.push_back(GenerateSamples(0x1337, samples));
     channel_data_.push_back(GenerateSamples(0x7331, samples));
 
     total_samples_ = samples;
 
@@ skipping 133 matching lines @@
       kDefaultChannels, kDefaultSampleRate, kDefaultBitsPerSample, kNumSamples);
 
   RecordAndVerifySamples();
 
   DeleteRecorder();
 }
 
 // TODO(rkc): Add tests with recording different sample rates.
 
 }  // namespace copresence