--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -2507,23 +2507,16 @@ void MediaDecoderStateMachine::Recompute
       duration < mObservedDuration.Ref()) {
     duration = mObservedDuration;
   }
 
   MOZ_ASSERT(duration.ToMicroseconds() >= 0);
   mDuration = Some(duration);
 }
 
-void
-MediaDecoderStateMachine::SetDormant(bool aDormant)
-{
-  MOZ_ASSERT(OnTaskQueue());
-  mStateObj->HandleDormant(aDormant);
-}
-
 RefPtr<ShutdownPromise>
 MediaDecoderStateMachine::Shutdown()
 {
   MOZ_ASSERT(OnTaskQueue());
   return mStateObj->HandleShutdown();
 }
 
 void MediaDecoderStateMachine::PlayStateChanged()

--- a/dom/media/MediaDecoderStateMachine.h
+++ b/dom/media/MediaDecoderStateMachine.h
@@ -276,18 +276,16 @@ private:
   // on the appropriate threads.
   bool OnTaskQueue() const;
 
   // Initialization that needs to happen on the task queue. This is the first
   // task that gets run on the task queue, and is dispatched from the MDSM
   // constructor immediately after the task queue is created.
   void InitializationTask(MediaDecoder* aDecoder);
 
-  void SetDormant(bool aDormant);
-
   void SetAudioCaptured(bool aCaptured);
 
   RefPtr<MediaDecoder::SeekPromise> Seek(SeekTarget aTarget);
 
   RefPtr<ShutdownPromise> Shutdown();
 
   RefPtr<ShutdownPromise> FinishShutdown();