Cleaned up the WebRtcAudioCapturer a bit.

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 1d904fa496202277130bc900edb0aea72b525472..05d7c6e86bf840471fd28203cbf3409a700f486c 100644
--- a/content/renderer/media/webrtc_audio_device_impl.h
+++ b/content/renderer/media/webrtc_audio_device_impl.h
@@ -299,14 +299,11 @@ class CONTENT_EXPORT WebRtcAudioDeviceImpl
   // Called on the main renderer thread.
   bool SetAudioRenderer(WebRtcAudioRenderer* renderer);
 
-  // Adds the capturer to the ADM.
+  // Adds/Removes the capturer to the ADM.
+  // TODO(xians): Remove these two methods once the ADM does not need to pass
+  // hardware information up to WebRtc.
   void AddAudioCapturer(const scoped_refptr<WebRtcAudioCapturer>& capturer);
-
-  // Gets the default capturer, which is the capturer in the list with
-  // a valid |device_id|. Microphones are represented by capturers with a valid
-  // |device_id|, since only one microphone is supported today, only one
-  // capturer in the |capturers_| can have a valid |device_id|.
-  scoped_refptr<WebRtcAudioCapturer> GetDefaultCapturer() const;
+  void RemoveAudioCapturer(const scoped_refptr<WebRtcAudioCapturer>& capturer);
 
   const scoped_refptr<WebRtcAudioRenderer>& renderer() const {
     return renderer_;
@@ -355,6 +352,10 @@ class CONTENT_EXPORT WebRtcAudioDeviceImpl
   virtual void SetRenderFormat(const media::AudioParameters& params) OVERRIDE;
   virtual void RemoveAudioRenderer(WebRtcAudioRenderer* renderer) OVERRIDE;
 
+  // Helper to get the default capturer, which is the capturer in the list with
+  // a valid |device_id|.
+  scoped_refptr<WebRtcAudioCapturer> GetDefaultCapturer() const;
+
   // Used to DCHECK that we are called on the correct thread.
   base::ThreadChecker thread_checker_;