Make AudioParameters a class instead of a struct

media/audio/mac/audio_low_latency_output_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.
 //
 // Implementation notes:
 //
 // - It is recommended to first acquire the native sample rate of the default
 //   output device and then use the same rate when creating this object.
 //   Use AUAudioOutputStream::HardwareSampleRate() to retrieve the sample rate.
 // - Calling Close() also leads to self destruction.
@@ skipping 28 matching lines @@
   virtual ~AUAudioOutputStream();
 
   // Implementation of AudioOutputStream.
   virtual bool Open() OVERRIDE;
   virtual void Close() OVERRIDE;
   virtual void Start(AudioSourceCallback* callback) OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual void SetVolume(double volume) OVERRIDE;
   virtual void GetVolume(double* volume) OVERRIDE;
 
-  static double HardwareSampleRate();
+  static int HardwareSampleRate();
 
  private:
   // DefaultOutputUnit callback.
   static OSStatus InputProc(void* user_data,
                             AudioUnitRenderActionFlags* flags,
                             const AudioTimeStamp* time_stamp,
                             UInt32 bus_number,
                             UInt32 number_of_frames,
                             AudioBufferList* io_data);
 
@@ skipping 30 matching lines @@
   // Volume level from 0 to 1.
   float volume_;
 
   // Fixed playout hardware latency in frames.
   double hardware_latency_frames_;
 
   DISALLOW_COPY_AND_ASSIGN(AUAudioOutputStream);
 };
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_OUTPUT_MAC_H_