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 59f8d168a028b916297afead450da12033c3ea30..0ae70b6786680684a8bd9f7447ae1fe56765cd8a 100644
--- a/media/audio/audio_input_controller.h
+++ b/media/audio/audio_input_controller.h
@@ -55,12 +55,12 @@
 //                              kRecording
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 // Close() ==>                  DoClose()
+//                              state_ = kClosed
 //                    AudioInputStream::Stop()
 //                    AudioInputStream::Close()
 //                    SyncWriter::Close()
-//                    Closure::Run()
-// (closure-task) <----------------.
-//                              kClosed
+// Closure::Run() <--------------.
+// (closure-task)
 //
 // The audio thread itself is owned by the AudioManager that the
 // AudioInputController holds a reference to.  When performing tasks on the
@@ -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);
 };