--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -867,18 +867,18 @@ nsresult MediaDecoderStateMachine::Init(
     OwnerThread(), __func__, this,
     &MediaDecoderStateMachine::OnCDMProxyReady,
     &MediaDecoderStateMachine::OnCDMProxyNotReady));
 #endif
 
   nsresult rv = mReader->Init();
   NS_ENSURE_SUCCESS(rv, rv);
 
-  OwnerThread()->Dispatch(NewRunnableMethod<State>(
-    this, &MediaDecoderStateMachine::EnterState, mState.Ref()));
+  OwnerThread()->Dispatch(
+    NewRunnableMethod(this, &MediaDecoderStateMachine::EnterState));
 
   return NS_OK;
 }
 
 void
 MediaDecoderStateMachine::SetMediaDecoderReaderWrapperCallback()
 {
   MOZ_ASSERT(OnTaskQueue());
@@ -1058,39 +1058,39 @@ MediaDecoderStateMachine::SetState(State
 {
   MOZ_ASSERT(OnTaskQueue());
   if (mState == aState) {
     return;
   }
 
   DECODER_LOG("MDSM state: %s -> %s", ToStateStr(), ToStateStr(aState));
 
-  ExitState(mState);
+  ExitState();
   mState = aState;
-  EnterState(mState);
+  EnterState();
 }
 
 void
-MediaDecoderStateMachine::ExitState(State aState)
+MediaDecoderStateMachine::ExitState()
 {
   MOZ_ASSERT(OnTaskQueue());
-  switch (aState) {
+  switch (mState) {
     case DECODER_STATE_COMPLETED:
       mSentPlaybackEndedEvent = false;
       break;
     default:
       break;
   }
 }
 
 void
-MediaDecoderStateMachine::EnterState(State aState)
+MediaDecoderStateMachine::EnterState()
 {
   MOZ_ASSERT(OnTaskQueue());
-  switch (aState) {
+  switch (mState) {
     case DECODER_STATE_DECODING_METADATA:
       ReadMetadata();
       break;
     case DECODER_STATE_DORMANT:
       DiscardSeekTaskIfExist();
       if (IsPlaying()) {
         StopPlayback();
       }

--- a/dom/media/MediaDecoderStateMachine.h
+++ b/dom/media/MediaDecoderStateMachine.h
@@ -351,18 +351,18 @@ private:
   // and aborting all pending operations on the decode task queue.
   void Reset(TrackSet aTracks = TrackSet(TrackInfo::kAudioTrack,
                                          TrackInfo::kVideoTrack));
 
 protected:
   virtual ~MediaDecoderStateMachine();
 
   void SetState(State aState);
-  void ExitState(State aState);
-  void EnterState(State aState);
+  void ExitState();
+  void EnterState();
 
   void BufferedRangeUpdated();
 
   void ReaderSuspendedChanged();
 
   // Inserts MediaData* samples into their respective MediaQueues.
   // aSample must not be null.