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

content/renderer/media/audio_input_device.h

Index: content/renderer/media/audio_input_device.h
diff --git a/content/renderer/media/audio_input_device.h b/content/renderer/media/audio_input_device.h
index ed855548fbaa3dea40fad0eceda59c633ea51f89..13b89b122228b1d26fe64e98283e7888656e72ed 100644
--- a/content/renderer/media/audio_input_device.h
+++ b/content/renderer/media/audio_input_device.h
@@ -69,6 +69,7 @@
 #define CONTENT_RENDERER_MEDIA_AUDIO_INPUT_DEVICE_H_
 #pragma once
 
+#include <string>
 #include <vector>
 
 #include "base/basictypes.h"
@@ -95,7 +96,8 @@ class CONTENT_EXPORT AudioInputDevice
    public:
     virtual void Capture(const std::vector<float*>& audio_data,
                          size_t number_of_frames,
-                         size_t audio_delay_milliseconds) = 0;
+                         size_t audio_delay_milliseconds,
+                         double volume) = 0;
     virtual void OnCaptureError() = 0;
    protected:
     virtual ~CaptureCallback() {}
@@ -144,11 +146,16 @@ class CONTENT_EXPORT AudioInputDevice
   // Returns |true| on success.
   bool GetVolume(double* volume);
 
+  // Sets the Automatic Gain Control state to on or off.
+  // This method must be called before Start(). It will not have any effect
+  // if it is called while capturing has already started.
+  void SetAutomaticGainControl(bool enabled);
+
   double sample_rate() const { return audio_parameters_.sample_rate; }
   size_t buffer_size() const { return audio_parameters_.samples_per_packet; }
 
   // Methods called on IO thread ----------------------------------------------
-  // AudioInputMessageFilter::Delegate impl., called by AudioInputMessageFilter
+  // AudioInputMessageFilter::Delegate impl., called by AudioInputMessageFilter.
   virtual void OnStreamCreated(base::SharedMemoryHandle handle,
                                base::SyncSocket::Handle socket_handle,
                                uint32 length) OVERRIDE;
@@ -166,6 +173,7 @@ class CONTENT_EXPORT AudioInputDevice
   void StartOnIOThread();
   void ShutDownOnIOThread();
   void SetVolumeOnIOThread(double volume);
+  void SetAutomaticGainControlOnIOThread(bool enabled);
 
   void Send(IPC::Message* message);
 
@@ -196,6 +204,10 @@ class CONTENT_EXPORT AudioInputDevice
   // callback. Only modified on the IO thread.
   bool pending_device_ready_;
 
+  // Stores the Automatic Gain Control state. Default is false.
+  // Only modified on the IO thread.
+  bool agc_is_enabled_;
+
   // Our audio thread callback class.  See source file for details.
   class AudioThreadCallback;