--- a/dom/media/systemservices/CamerasParent.h
+++ b/dom/media/systemservices/CamerasParent.h
@@ -69,18 +69,19 @@ public:
   friend CamerasParent;
 
 private:
   ~InputObserver() {}
 
   RefPtr<CamerasParent> mParent;
 };
 
-class CamerasParent :  public PCamerasParent,
-                       public nsIObserver
+class CamerasParent final
+  : public PCamerasParent
+  , public nsIObserver
 {
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIOBSERVER
 
 public:
   static already_AddRefed<CamerasParent> Create();
 
   // Messages received form the child. These run on the IPC/PBackground thread.