diff --git a/dom/media/MediaStreamGraph.cpp b/dom/media/MediaStreamGraph.cpp
index 82d598255b1c..99f6d08e0f0e 100644
--- a/dom/media/MediaStreamGraph.cpp
+++ b/dom/media/MediaStreamGraph.cpp
@@ -1950,6 +1950,12 @@ MediaStream::FinishOnGraphThread()
   GraphImpl()->FinishStream(this);
 }
 
+StreamBuffer::Track*
+MediaStream::FindTrack(TrackID aID)
+{
+  return mBuffer.FindTrack(aID);
+}
+
 StreamBuffer::Track*
 MediaStream::EnsureTrack(TrackID aTrackId)
 {
@@ -2582,12 +2588,6 @@ SourceMediaStream::FinishAddTracks()
   }
 }
 
-StreamBuffer::Track*
-SourceMediaStream::FindTrack(TrackID aID)
-{
-  return mBuffer.FindTrack(aID);
-}
-
 void
 SourceMediaStream::ResampleAudioToGraphSampleRate(TrackData* aTrackData, MediaSegment* aSegment)
 {
diff --git a/dom/media/MediaStreamGraph.h b/dom/media/MediaStreamGraph.h
index 850dbb746779..87c04c584c48 100644
--- a/dom/media/MediaStreamGraph.h
+++ b/dom/media/MediaStreamGraph.h
@@ -758,6 +758,11 @@ public:
 
   bool HasCurrentData() { return mHasCurrentData; }
 
+  /**
+   * Find track by track id.
+   */
+  StreamBuffer::Track* FindTrack(TrackID aID);
+
   StreamBuffer::Track* EnsureTrack(TrackID aTrack);
 
   virtual void ApplyTrackDisabling(TrackID aTrackID, MediaSegment* aSegment, MediaSegment* aRawSegment = nullptr);
@@ -1000,11 +1005,6 @@ public:
    */
   void FinishAddTracks();
 
-  /**
-   * Find track by track id.
-   */
-  StreamBuffer::Track* FindTrack(TrackID aID);
-
   /**
    * Append media data to a track. Ownership of aSegment remains with the caller,
    * but aSegment is emptied.