Use AudioUnit instead of AudioDevice properties to get channel count.

media/audio/mac/audio_auhal_mac.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/mac/audio_auhal_mac.h"
 
 #include <CoreServices/CoreServices.h>
 
 #include <algorithm>
 #include <cstddef>
@@ skipping 96 matching lines @@
 
   ReportAndResetStats();
 }
 
 bool AUHALStream::Open() {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(!output_bus_.get());
   DCHECK(!audio_unit_);
   DVLOG(1) << "Open";
 
-  // Get the total number of output channels that the

[DaleCurtis, 2017/03/23 22:15:03]

Deleted this since it's enforced by the AudioOutputResampler.

-  // hardware supports.
-  int device_output_channels;
-  bool got_output_channels = AudioManagerMac::GetDeviceChannels(
-      device_,
-      kAudioDevicePropertyScopeOutput,
-      &device_output_channels);
-
-  // Sanity check the requested output channels.
-  if (!got_output_channels ||
-      output_channels_ <= 0 || output_channels_ > device_output_channels) {
-    LOG(ERROR) << "AudioDevice does not support requested output channels.";
-    return false;
-  }
-
-  // The requested sample-rate must match the hardware sample-rate.
-  int sample_rate = AudioManagerMac::HardwareSampleRateForDevice(device_);
-
-  if (sample_rate != params_.sample_rate()) {
-    LOG(ERROR) << "Requested sample-rate: " << params_.sample_rate()
-               << " must match the hardware sample-rate: " << sample_rate;
-    return false;
-  }
-
   // The output bus will wrap the AudioBufferList given to us in
   // the Render() callback.
   DCHECK_GT(output_channels_, 0);
   output_bus_ = AudioBus::CreateWrapper(output_channels_);
 
   bool configured = ConfigureAUHAL();
   if (configured)
     hardware_latency_ = GetHardwareLatency();
 
   return configured;
@@ skipping 486 matching lines @@
   OSStatus result = AudioUnitSetProperty(
       audio_unit_, kAudioUnitProperty_AudioChannelLayout, kAudioUnitScope_Input,
       0, channel_layout, layout_size);
   if (result != noErr) {
     OSSTATUS_DLOG(ERROR, result)
         << "Failed to set audio channel layout. Using default layout.";
   }
 }
 
 }  // namespace media