--- a/dom/media/eme/MediaKeys.h
+++ b/dom/media/eme/MediaKeys.h
@@ -128,18 +128,16 @@ public:
   // Shutdown which is called from the script/dom side.
   void Terminated();
 
   // Returns true if this MediaKeys has been bound to a media element.
   bool IsBoundToMediaElement() const;
 
 private:
 
-  bool IsInPrivateBrowsing();
-
   // Removes promise from mPromises, and returns it.
   already_AddRefed<DetailedPromise> RetrievePromise(PromiseId aId);
 
   // Owning ref to proxy. The proxy has a weak reference back to the MediaKeys,
   // and the MediaKeys destructor clears the proxy's reference to the MediaKeys.
   RefPtr<CDMProxy> mProxy;
 
   RefPtr<HTMLMediaElement> mElement;