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

media/audio/audio_input_controller.h

Index: media/audio/audio_input_controller.h
diff --git a/media/audio/audio_input_controller.h b/media/audio/audio_input_controller.h
index feeb895c6b71ea7bfbf8eb323f06c09f0721bc1d..8fd69b0fa6299151822f8bc6ec8c97247ff6cb91 100644
--- a/media/audio/audio_input_controller.h
+++ b/media/audio/audio_input_controller.h
@@ -97,7 +97,7 @@ class MEDIA_EXPORT AudioInputController
 
     // Write certain amount of data from |data|. This method returns
     // number of written bytes.
-    virtual uint32 Write(const void* data, uint32 size) = 0;
+    virtual uint32 Write(const void* data, uint32 size, double volume) = 0;
 
     // Close this synchronous writer.
     virtual void Close() = 0;
@@ -157,10 +157,18 @@ class MEDIA_EXPORT AudioInputController
   // This method trampolines to the audio thread.
   virtual void Close(const base::Closure& closed_task);
 
+  // Sets the capture volume of the input stream. The value 0.0 corresponds
+  // to muted and 1.0 to maximum volume.
+  virtual void SetVolume(double volume);
+
+  // Sets the Automatic Gain Control (AGC) state of the input stream.
+  // Changing the AGC state is not supported while recording is active.
+  virtual void SetAutomaticGainControl(bool enabled);
+
   // AudioInputCallback implementation. Threading details depends on the
   // device-specific implementation.
   virtual void OnData(AudioInputStream* stream, const uint8* src, uint32 size,
-                      uint32 hardware_delay_bytes) OVERRIDE;
+                      uint32 hardware_delay_bytes, double volume) OVERRIDE;
   virtual void OnClose(AudioInputStream* stream) OVERRIDE;
   virtual void OnError(AudioInputStream* stream, int code) OVERRIDE;
 
@@ -187,6 +195,8 @@ class MEDIA_EXPORT AudioInputController
   void DoRecord();
   void DoClose();
   void DoReportError(int code);
+  void DoSetVolume(double volume);
+  void DoSetAutomaticGainControl(bool enabled);
 
   // Methods which ensures that OnError() is triggered when data recording
   // times out. Both are called on the creating thread.
@@ -229,6 +239,8 @@ class MEDIA_EXPORT AudioInputController
 
   static Factory* factory_;
 
+  double max_volume_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioInputController);
 };