--- a/dom/media/mediasource/MediaSourceDecoder.cpp
+++ b/dom/media/mediasource/MediaSourceDecoder.cpp
@@ -50,17 +50,17 @@ MediaSourceDecoder::CreateStateMachine()
 nsresult
 MediaSourceDecoder::Load(nsIPrincipal* aPrincipal)
 {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(!GetStateMachine());
   AbstractThread::AutoEnter context(AbstractMainThread());
 
   mPrincipal = aPrincipal;
-  mResource = new MediaSourceResource();
+  mResource = MakeUnique<MediaSourceResource>();
 
   nsresult rv = MediaShutdownManager::Instance().Register(this);
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return rv;
   }
 
   SetStateMachine(CreateStateMachine());
   if (!GetStateMachine()) {

--- a/dom/media/mediasource/MediaSourceDecoder.h
+++ b/dom/media/mediasource/MediaSourceDecoder.h
@@ -69,17 +69,17 @@ private:
   void PinForSeek() override {}
   void UnpinForSeek() override {}
   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;
+  UniquePtr<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;
 

--- a/dom/media/mediasource/MediaSourceResource.h
+++ b/dom/media/mediasource/MediaSourceResource.h
@@ -2,78 +2,45 @@
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef MOZILLA_MEDIASOURCERESOURCE_H_
 #define MOZILLA_MEDIASOURCERESOURCE_H_
 
-#include "MediaResource.h"
 #include "mozilla/Monitor.h"
-#include "mozilla/Logging.h"
-
-extern mozilla::LogModule* GetMediaSourceLog();
-
-#define MSE_DEBUG(arg, ...)                                                    \
-  MOZ_LOG(                                                                     \
-    GetMediaSourceLog(),                                                       \
-    mozilla::LogLevel::Debug,                                                  \
-    ("MediaSourceResource(%p)::%s: " arg, this, __func__, ##__VA_ARGS__))
-
-#define UNIMPLEMENTED() MSE_DEBUG("UNIMPLEMENTED FUNCTION at %s:%d", __FILE__, __LINE__)
 
 namespace mozilla {
 
-class MediaSourceResource final : public MediaResource
+class MediaSourceResource final
 {
 public:
   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; }
-
-  nsresult GetCachedRanges(MediaByteRangeSet& aRanges) override
-  {
-    UNIMPLEMENTED();
-    aRanges += MediaByteRange(0, GetLength());
-    return NS_OK;
-  }
-
   void SetEnded(bool aEnded)
   {
     MonitorAutoLock mon(mMonitor);
     mEnded = aEnded;
   }
 
-private:
   size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
   {
     // TODO: track source buffers appended to MediaSource.
     return 0;
   }
 
   size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
   {
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
   }
 
+private:
   Monitor mMonitor;
   bool mEnded; // protected by mMonitor
 };
 
 } // namespace mozilla
 
-#undef MSE_DEBUG
-#undef UNIMPLEMENTED
-
 #endif /* MOZILLA_MEDIASOURCERESOURCE_H_ */