Detect AudioInputStream muting and propagate to MediaStreamAudioSource.

media/base/audio_capturer_source.h

Index: media/base/audio_capturer_source.h
diff --git a/media/base/audio_capturer_source.h b/media/base/audio_capturer_source.h
index d355a1b06a296e5bbcb0f6084e36f282dfde0574..6e34ddcd26e784be27a6f699344a12dcfecca989 100644
--- a/media/base/audio_capturer_source.h
+++ b/media/base/audio_capturer_source.h
@@ -41,6 +41,9 @@ class AudioCapturerSource
     // Signals an error has occurred.
     virtual void OnCaptureError(const std::string& message) = 0;
 
+    // Signals the muted state has changed.
+    virtual void OnCaptureMuted(bool is_muted) = 0;
+
    protected:
     virtual ~CaptureCallback() {}
   };