--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -236,18 +236,16 @@ MediaDecoderStateMachine::MediaDecoderSt
   mDecodeToSeekTarget(false),
   mCurrentTimeBeforeSeek(0),
   mCorruptFrames(60),
   mDecodingFirstFrame(true),
   mSentLoadedMetadataEvent(false),
   mSentFirstFrameLoadedEvent(false, "MediaDecoderStateMachine::mSentFirstFrameLoadedEvent"),
   mSentPlaybackEndedEvent(false),
   mOutputStreamManager(new OutputStreamManager()),
-  mStreamSink(new DecodedStream(
-    mTaskQueue, mAudioQueue, mVideoQueue, mOutputStreamManager)),
   mResource(aDecoder->GetResource()),
   mAudioOffloading(false),
   mBuffered(mTaskQueue, TimeIntervals(),
             "MediaDecoderStateMachine::mBuffered (Mirror)"),
   mEstimatedDuration(mTaskQueue, NullableTimeUnit(),
                     "MediaDecoderStateMachine::mEstimatedDuration (Mirror)"),
   mExplicitDuration(mTaskQueue, Maybe<double>(),
                     "MediaDecoderStateMachine::mExplicitDuration (Mirror)"),
@@ -334,16 +332,19 @@ MediaDecoderStateMachine::~MediaDecoderS
 #endif
 }
 
 void
 MediaDecoderStateMachine::InitializationTask(MediaDecoder* aDecoder)
 {
   MOZ_ASSERT(OnTaskQueue());
 
+  mStreamSink = new DecodedStream(mTaskQueue, mAudioQueue, mVideoQueue,
+                                  mOutputStreamManager, mSameOriginMedia.Ref());
+
   // Connect mirrors.
   mBuffered.Connect(mReader->CanonicalBuffered());
   mEstimatedDuration.Connect(aDecoder->CanonicalEstimatedDuration());
   mExplicitDuration.Connect(aDecoder->CanonicalExplicitDuration());
   mPlayState.Connect(aDecoder->CanonicalPlayState());
   mNextPlayState.Connect(aDecoder->CanonicalNextPlayState());
   mLogicallySeeking.Connect(aDecoder->CanonicalLogicallySeeking());
   mVolume.Connect(aDecoder->CanonicalVolume());

--- a/dom/media/mediasink/DecodedStream.cpp
+++ b/dom/media/mediasink/DecodedStream.cpp
@@ -183,21 +183,22 @@ DecodedStreamData::SetPlaying(bool aPlay
     mPlaying = aPlaying;
     UpdateStreamSuspended(mStream, !mPlaying);
   }
 }
 
 DecodedStream::DecodedStream(AbstractThread* aOwnerThread,
                              MediaQueue<MediaData>& aAudioQueue,
                              MediaQueue<MediaData>& aVideoQueue,
-                             OutputStreamManager* aOutputStreamManager)
+                             OutputStreamManager* aOutputStreamManager,
+                             const bool& aSameOrigin)
   : mOwnerThread(aOwnerThread)
   , mOutputStreamManager(aOutputStreamManager)
   , mPlaying(false)
-  , mSameOrigin(false)
+  , mSameOrigin(aSameOrigin)
   , mAudioQueue(aAudioQueue)
   , mVideoQueue(aVideoQueue)
 {
 }
 
 DecodedStream::~DecodedStream()
 {
   MOZ_ASSERT(mStartTime.isNothing(), "playback should've ended.");

--- a/dom/media/mediasink/DecodedStream.h
+++ b/dom/media/mediasink/DecodedStream.h
@@ -30,17 +30,18 @@ template <class T> class MediaQueue;
 
 class DecodedStream : public media::MediaSink {
   using media::MediaSink::PlaybackParams;
 
 public:
   DecodedStream(AbstractThread* aOwnerThread,
                 MediaQueue<MediaData>& aAudioQueue,
                 MediaQueue<MediaData>& aVideoQueue,
-                OutputStreamManager* aOutputStreamManager);
+                OutputStreamManager* aOutputStreamManager,
+                const bool& aSameOrigin);
 
   // MediaSink functions.
   const PlaybackParams& GetPlaybackParams() const override;
   void SetPlaybackParams(const PlaybackParams& aParams) override;
 
   RefPtr<GenericPromise> OnEnded(TrackType aType) override;
   int64_t GetEndTime(TrackType aType) const override;
   int64_t GetPosition(TimeStamp* aTimeStamp = nullptr) const override;
@@ -93,17 +94,17 @@ private:
 
   /*
    * Worker thread only members.
    */
   UniquePtr<DecodedStreamData> mData;
   RefPtr<GenericPromise> mFinishPromise;
 
   bool mPlaying;
-  bool mSameOrigin;
+  const bool& mSameOrigin; // valid until Shutdown() is called.
   PlaybackParams mParams;
 
   Maybe<int64_t> mStartTime;
   MediaInfo mInfo;
 
   MediaQueue<MediaData>& mAudioQueue;
   MediaQueue<MediaData>& mVideoQueue;