Adds Analog Gain Control (AGC) to the WebRTC client.

media/audio/mac/audio_low_latency_input_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 of AudioInputStream for Mac OS X using the special AUHAL
 // input Audio Unit present in OS 10.4 and later.
 // The AUHAL input Audio Unit is for low-latency audio I/O.
 //
 // Overview of operation:
 //
@@ skipping 20 matching lines @@
 //   1) Hardware latency, which includes Audio Unit latency, audio device
 //      latency;
 //   2) The delay between the actual recording instant and the time when the
 //      data packet is provided as a callback.
 //
 #ifndef MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_
 #define MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_
 
 #include <AudioUnit/AudioUnit.h>
 
+#include "base/atomicops.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/lock.h"
+#include "base/time.h"
 #include "media/audio/audio_io.h"
+#include "media/audio/audio_input_stream_impl.h"
 #include "media/audio/audio_parameters.h"
 
 class AudioManagerMac;
 
-class AUAudioInputStream : public AudioInputStream {
+class AUAudioInputStream : public AudioInputStreamImpl {
  public:
   // The ctor takes all the usual parameters, plus |manager| which is the
   // the audio manager who is creating this object.
   AUAudioInputStream(AudioManagerMac* manager,
                      const AudioParameters& params,
                      AudioDeviceID audio_device_id);
   // The dtor is typically called by the AudioManager only and it is usually
   // triggered by calling AudioInputStream::Close().
   virtual ~AUAudioInputStream();
 
@@ skipping 78 matching lines @@
   double hardware_latency_frames_;
 
   // The number of channels in each frame of audio data, which is used
   // when querying the volume of each channel.
   int number_of_channels_in_frame_;
 
   DISALLOW_COPY_AND_ASSIGN(AUAudioInputStream);
 };
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_