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

content/renderer/media/webrtc_audio_device_impl.h

Index: content/renderer/media/webrtc_audio_device_impl.h
diff --git a/content/renderer/media/webrtc_audio_device_impl.h b/content/renderer/media/webrtc_audio_device_impl.h
index 36e37eac9132463ce0917649d061db66189e25db..1476debcf3bd1506ff4f8cb0655177b0254401d9 100644
--- a/content/renderer/media/webrtc_audio_device_impl.h
+++ b/content/renderer/media/webrtc_audio_device_impl.h
@@ -120,7 +120,8 @@ class CONTENT_EXPORT WebRtcAudioDeviceImpl
   // AudioInputDevice::CaptureCallback implementation.
   virtual void Capture(const std::vector<float*>& audio_data,
                        size_t number_of_frames,
-                       size_t audio_delay_milliseconds) OVERRIDE;
+                       size_t audio_delay_milliseconds,
+                       double volume) OVERRIDE;
   virtual void OnCaptureError() OVERRIDE;
 
   // AudioInputDevice::CaptureEventHandler implementation.
@@ -330,6 +331,9 @@ class CONTENT_EXPORT WebRtcAudioDeviceImpl
   bool playing_;
   bool recording_;
 
+  // Local copy of the current Automatic Gain Control state.
+  bool agc_is_enabled_;
+
   DISALLOW_COPY_AND_ASSIGN(WebRtcAudioDeviceImpl);
 };