--- a/dom/media/MediaDecoder.h
+++ b/dom/media/MediaDecoder.h
@@ -250,17 +250,17 @@ public:
   // Return the duration of the video in seconds.
   virtual double GetDuration();
 
   // Return true if the stream is infinite (see SetInfinite).
   bool IsInfinite() const;
 
   // Called by MediaResource when some data has been received.
   // Call on the main thread only.
-  virtual void NotifyDownloadProgressed();
+  void NotifyDownloadProgressed();
 
   // Called as data arrives on the stream and is read into the cache.  Called
   // on the main thread only.
   void NotifyDataArrived();
 
   // Return true if we are currently seeking in the media resource.
   // Call on the main thread only.
   bool IsSeeking() const;