--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -1576,38 +1576,52 @@ MediaDecoder::SetPlaybackRate(double aPl
 void
 MediaDecoder::SetPreservesPitch(bool aPreservesPitch)
 {
   MOZ_ASSERT(NS_IsMainThread());
   mPreservesPitch = aPreservesPitch;
 }
 
 void
+MediaDecoder::ConnectMirrors(MediaDecoderStateMachine* aObject)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aObject);
+  mStateMachineDuration.Connect(aObject->CanonicalDuration());
+  mBuffered.Connect(aObject->CanonicalBuffered());
+  mStateMachineIsShutdown.Connect(aObject->CanonicalIsShutdown());
+  mNextFrameStatus.Connect(aObject->CanonicalNextFrameStatus());
+  mCurrentPosition.Connect(aObject->CanonicalCurrentPosition());
+  mPlaybackPosition.Connect(aObject->CanonicalPlaybackOffset());
+  mIsAudioDataAudible.Connect(aObject->CanonicalIsAudioDataAudible());
+}
+
+void
+MediaDecoder::DisconnectMirrors()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  mStateMachineDuration.DisconnectIfConnected();
+  mBuffered.DisconnectIfConnected();
+  mStateMachineIsShutdown.DisconnectIfConnected();
+  mNextFrameStatus.DisconnectIfConnected();
+  mCurrentPosition.DisconnectIfConnected();
+  mPlaybackPosition.DisconnectIfConnected();
+  mIsAudioDataAudible.DisconnectIfConnected();
+}
+
+void
 MediaDecoder::SetStateMachine(MediaDecoderStateMachine* aStateMachine)
 {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT_IF(aStateMachine, !mDecoderStateMachine);
   mDecoderStateMachine = aStateMachine;
-
-  if (mDecoderStateMachine) {
-    mStateMachineDuration.Connect(mDecoderStateMachine->CanonicalDuration());
-    mBuffered.Connect(mDecoderStateMachine->CanonicalBuffered());
-    mStateMachineIsShutdown.Connect(mDecoderStateMachine->CanonicalIsShutdown());
-    mNextFrameStatus.Connect(mDecoderStateMachine->CanonicalNextFrameStatus());
-    mCurrentPosition.Connect(mDecoderStateMachine->CanonicalCurrentPosition());
-    mPlaybackPosition.Connect(mDecoderStateMachine->CanonicalPlaybackOffset());
-    mIsAudioDataAudible.Connect(mDecoderStateMachine->CanonicalIsAudioDataAudible());
+  if (aStateMachine) {
+    ConnectMirrors(aStateMachine);
   } else {
-    mStateMachineDuration.DisconnectIfConnected();
-    mBuffered.DisconnectIfConnected();
-    mStateMachineIsShutdown.DisconnectIfConnected();
-    mNextFrameStatus.DisconnectIfConnected();
-    mCurrentPosition.DisconnectIfConnected();
-    mPlaybackPosition.DisconnectIfConnected();
-    mIsAudioDataAudible.DisconnectIfConnected();
+    DisconnectMirrors();
   }
 }
 
 ImageContainer*
 MediaDecoder::GetImageContainer()
 {
   return mVideoFrameContainer ? mVideoFrameContainer->GetImageContainer() : nullptr;
 }

--- a/dom/media/MediaDecoder.h
+++ b/dom/media/MediaDecoder.h
@@ -598,16 +598,19 @@ private:
 
   void OnMediaNotSeekable()
   {
     SetMediaSeekable(false);
   }
 
   void FinishShutdown();
 
+  void ConnectMirrors(MediaDecoderStateMachine* aObject);
+  void DisconnectMirrors();
+
   MediaEventProducer<void> mDataArrivedEvent;
 
   // The state machine object for handling the decoding. It is safe to
   // call methods of this object from other threads. Its internal data
   // is synchronised on a monitor. The lifetime of this object is
   // after mPlayState is LOADING and before mPlayState is SHUTDOWN. It
   // is safe to access it during this period.
   //