--- a/dom/media/MediaStreamTrack.cpp
+++ b/dom/media/MediaStreamTrack.cpp
@@ -252,10 +252,19 @@ void
 MediaStreamTrack::RemoveListener(MediaStreamTrackListener* aListener)
 {
   LOG(LogLevel::Debug, ("MediaStreamTrack %p removing listener %p",
                         this, aListener));
 
   GetOwnedStream()->RemoveTrackListener(aListener, mTrackID);
 }
 
+already_AddRefed<MediaInputPort>
+MediaStreamTrack::ForwardTrackContentsTo(ProcessedMediaStream* aStream)
+{
+  MOZ_RELEASE_ASSERT(aStream);
+  RefPtr<MediaInputPort> port =
+    aStream->AllocateInputPort(GetOwnedStream(), mTrackID);
+  return port.forget();
+}
+
 } // namespace dom
 } // namespace mozilla

--- a/dom/media/MediaStreamTrack.h
+++ b/dom/media/MediaStreamTrack.h
@@ -13,16 +13,17 @@
 #include "MediaTrackConstraints.h"
 #include "mozilla/CORSMode.h"
 #include "PrincipalChangeObserver.h"
 
 namespace mozilla {
 
 class DOMMediaStream;
 class MediaEnginePhotoCallback;
+class MediaInputPort;
 class MediaStream;
 class MediaStreamGraph;
 class MediaStreamTrackListener;
 class PeerConnectionImpl;
 class ProcessedMediaStream;
 class RemoteSourceStreamInfo;
 
 namespace dom {
@@ -278,16 +279,22 @@ public:
   void AddListener(MediaStreamTrackListener* aListener);
 
   /**
    * Removes a MediaStreamTrackListener from the MediaStreamGraph representation
    * of this track.
    */
   void RemoveListener(MediaStreamTrackListener* aListener);
 
+  /**
+   * Sets up a MediaInputPort from the underlying track that this
+   * MediaStreamTrack represents, to aStream, and returns it.
+   */
+  already_AddRefed<MediaInputPort> ForwardTrackContentsTo(ProcessedMediaStream* aStream);
+
 protected:
   virtual ~MediaStreamTrack();
 
   // Returns the original DOMMediaStream's underlying input stream.
   MediaStream* GetInputStream();
 
   // Returns the owning DOMMediaStream's underlying owned stream.
   ProcessedMediaStream* GetOwnedStream();