--- a/dom/media/mediasource/MediaSourceDecoder.cpp
+++ b/dom/media/mediasource/MediaSourceDecoder.cpp
@@ -55,17 +55,18 @@ MediaSourceDecoder::CreateStateMachine()
 
 nsresult
 MediaSourceDecoder::Load(nsIPrincipal* aPrincipal)
 {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(!GetStateMachine());
   AbstractThread::AutoEnter context(AbstractMainThread());
 
-  mResource = new MediaSourceResource(aPrincipal);
+  mPrincipal = aPrincipal;
+  mResource = new MediaSourceResource();
 
   nsresult rv = MediaShutdownManager::Instance().Register(this);
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return rv;
   }
 
   SetStateMachine(CreateStateMachine());
   if (!GetStateMachine()) {
@@ -361,15 +362,15 @@ MediaSourceDecoder::NotifyInitDataArrive
     mDemuxer->NotifyInitDataArrived();
   }
 }
 
 already_AddRefed<nsIPrincipal>
 MediaSourceDecoder::GetCurrentPrincipal()
 {
   MOZ_ASSERT(NS_IsMainThread());
-  return mResource ? mResource->GetCurrentPrincipal() : nullptr;
+  return do_AddRef(mPrincipal);
 }
 
 #undef MSE_DEBUG
 #undef MSE_DEBUGV
 
 } // namespace mozilla

--- a/dom/media/mediasource/MediaSourceDecoder.h
+++ b/dom/media/mediasource/MediaSourceDecoder.h
@@ -69,16 +69,17 @@ private:
   MediaResource* GetResource() const override final;
   MediaDecoderStateMachine* CreateStateMachine();
   void DoSetMediaSourceDuration(double aDuration);
   media::TimeInterval ClampIntervalToEnd(const media::TimeInterval& aInterval);
   bool CanPlayThroughImpl() override;
   bool IsLiveStream() override final { return !mEnded; }
 
   RefPtr<MediaSourceResource> mResource;
+  RefPtr<nsIPrincipal> mPrincipal;
 
   // The owning MediaSource holds a strong reference to this decoder, and
   // calls Attach/DetachMediaSource on this decoder to set and clear
   // mMediaSource.
   dom::MediaSource* mMediaSource;
   RefPtr<MediaSourceDemuxer> mDemuxer;
 
   bool mEnded;

--- a/dom/media/mediasource/MediaSourceResource.h
+++ b/dom/media/mediasource/MediaSourceResource.h
@@ -21,38 +21,32 @@ extern mozilla::LogModule* GetMediaSourc
 
 #define UNIMPLEMENTED() MSE_DEBUG("UNIMPLEMENTED FUNCTION at %s:%d", __FILE__, __LINE__)
 
 namespace mozilla {
 
 class MediaSourceResource final : public MediaResource
 {
 public:
-  explicit MediaSourceResource(nsIPrincipal* aPrincipal = nullptr)
-    : mPrincipal(aPrincipal)
-    , mMonitor("MediaSourceResource")
+  MediaSourceResource()
+    : mMonitor("MediaSourceResource")
     , mEnded(false)
-    {}
+  {}
 
   nsresult ReadAt(int64_t aOffset, char* aBuffer, uint32_t aCount, uint32_t* aBytes) override { UNIMPLEMENTED(); return NS_ERROR_FAILURE; }
   bool ShouldCacheReads() override { UNIMPLEMENTED(); return false; }
   int64_t Tell() override { UNIMPLEMENTED(); return -1; }
   void Pin() override { UNIMPLEMENTED(); }
   void Unpin() override { UNIMPLEMENTED(); }
   int64_t GetLength() override { UNIMPLEMENTED(); return -1; }
   int64_t GetNextCachedData(int64_t aOffset) override { UNIMPLEMENTED(); return -1; }
   int64_t GetCachedDataEnd(int64_t aOffset) override { UNIMPLEMENTED(); return -1; }
   bool IsDataCachedToEndOfResource(int64_t aOffset) override { UNIMPLEMENTED(); return false; }
   nsresult ReadFromCache(char* aBuffer, int64_t aOffset, uint32_t aCount) override { UNIMPLEMENTED(); return NS_ERROR_FAILURE; }
 
-  already_AddRefed<nsIPrincipal> GetCurrentPrincipal()
-  {
-    return RefPtr<nsIPrincipal>(mPrincipal).forget();
-  }
-
   nsresult GetCachedRanges(MediaByteRangeSet& aRanges) override
   {
     UNIMPLEMENTED();
     aRanges += MediaByteRange(0, GetLength());
     return NS_OK;
   }
 
   void SetEnded(bool aEnded)
@@ -68,17 +62,16 @@ private:
     return size;
   }
 
   size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
   {
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
   }
 
-  RefPtr<nsIPrincipal> mPrincipal;
   Monitor mMonitor;
   bool mEnded; // protected by mMonitor
 };
 
 } // namespace mozilla
 
 #undef MSE_DEBUG
 #undef UNIMPLEMENTED