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

media/audio/mac/audio_input_mac.cc

 // 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.
 
 #include "media/audio/mac/audio_input_mac.h"
 
 #include <CoreServices/CoreServices.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
@@ skipping 109 matching lines @@
 
 void PCMQueueInAudioInputStream::SetVolume(double volume) {
   NOTREACHED() << "Only supported for low-latency mode.";
 }
 
 double PCMQueueInAudioInputStream::GetVolume() {
   NOTREACHED() << "Only supported for low-latency mode.";
   return 0.0;
 }
 
+void PCMQueueInAudioInputStream::SetAutomaticGainControl(bool enabled) {
+  NOTREACHED() << "Only supported for low-latency mode.";
+}
+
+bool PCMQueueInAudioInputStream::GetAutomaticGainControl() {
+  NOTREACHED() << "Only supported for low-latency mode.";
+  return false;
+}
+
 void PCMQueueInAudioInputStream::HandleError(OSStatus err) {
   if (callback_)
     callback_->OnError(this, static_cast<int>(err));
   NOTREACHED() << "error " << GetMacOSStatusErrorString(err)
                << " (" << err << ")";
 }
 
 bool PCMQueueInAudioInputStream::SetupBuffers() {
   DCHECK(buffer_size_bytes_);
   for (int i = 0; i < kNumberBuffers; ++i) {
@@ skipping 42 matching lines @@
   if (!callback_) {
     // This can happen if Stop() was called without start.
     DCHECK_EQ(0U, audio_buffer->mAudioDataByteSize);
     return;
   }
 
   if (audio_buffer->mAudioDataByteSize)
     callback_->OnData(this,
                       reinterpret_cast<const uint8*>(audio_buffer->mAudioData),
                       audio_buffer->mAudioDataByteSize,
-                      audio_buffer->mAudioDataByteSize);
+                      audio_buffer->mAudioDataByteSize,
+                      0.0);
   // Recycle the buffer.
   OSStatus err = QueueNextBuffer(audio_buffer);
   if (err != noErr) {
     if (err == kAudioQueueErr_EnqueueDuringReset) {
       // This is the error you get if you try to enqueue a buffer and the
       // queue has been closed. Not really a problem if indeed the queue
       // has been closed.
       // TODO(joth): PCMQueueOutAudioOutputStream uses callback_ to provide an
       // extra guard for this situation, but it seems to introduce more
       // complications than it solves (memory barrier issues accessing it from
       // multiple threads, looses the means to indicate OnClosed to client).
       // Should determine if we need to do something equivalent here.
       return;
     }
     HandleError(err);
   }
 }