Increase the default buffer size from 128 to 256 on Mac

media/audio/mac/audio_manager_mac.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.
 
 #ifndef MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_
 #define MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_
 
 #include <CoreAudio/AudioHardware.h>
 #include <list>
 #include <string>
@@ skipping 68 matching lines @@
   ~AudioManagerMac() override;
 
   AudioParameters GetPreferredOutputStreamParameters(
       const std::string& output_device_id,
       const AudioParameters& input_params) override;
 
  private:
   void InitializeOnAudioThread();
   void ShutdownOnAudioThread();
 
-  int ChooseBufferSize(int output_sample_rate);
+  int ChooseBufferSize(bool is_input, int sample_rate);
 
   // Notify streams of a device change if the default output device or its
   // sample rate has changed, otherwise does nothing.
   void HandleDeviceChanges();
 
   scoped_ptr<AudioDeviceListenerMac> output_device_listener_;
 
   // Track the output sample-rate and the default output device
   // so we can intelligently handle device notifications only when necessary.
   int current_sample_rate_;
   AudioDeviceID current_output_device_;
 
   // Helper class which monitors power events to determine if output streams
   // should defer Start() calls.  Required to workaround an OSX bug.  See
   // http://crbug.com/160920 for more details.
   class AudioPowerObserver;
   scoped_ptr<AudioPowerObserver> power_observer_;
 
   // Tracks all constructed input and output streams so they can be stopped at
   // shutdown.  See ShutdownOnAudioThread() for more details.
   std::list<AudioInputStream*> input_streams_;
   std::list<AudioOutputStream*> output_streams_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerMac);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_