--- a/dom/media/mediasource/SourceBuffer.cpp
+++ b/dom/media/mediasource/SourceBuffer.cpp
@@ -412,17 +412,17 @@ SourceBuffer::AppendData(const uint8_t* 
   MSE_DEBUG("AppendData(aLength=%u)", aLength);
 
   RefPtr<MediaByteBuffer> data = PrepareAppend(aData, aLength, aRv);
   if (!data) {
     return;
   }
   StartUpdating();
 
-  mTrackBuffersManager->AppendData(data, mCurrentAttributes)
+  mTrackBuffersManager->AppendData(data.forget(), mCurrentAttributes)
     ->Then(mAbstractMainThread, __func__, this,
            &SourceBuffer::AppendDataCompletedWithSuccess,
            &SourceBuffer::AppendDataErrored)
     ->Track(mPendingAppend);
 }
 
 void
 SourceBuffer::AppendDataCompletedWithSuccess(const SourceBufferTask::AppendBufferResult& aResult)

--- a/dom/media/mediasource/SourceBufferTask.h
+++ b/dom/media/mediasource/SourceBufferTask.h
@@ -42,17 +42,17 @@ public:
   }
 
 protected:
   virtual ~SourceBufferTask() {}
 };
 
 class AppendBufferTask : public SourceBufferTask {
 public:
-  AppendBufferTask(MediaByteBuffer* aData,
+  AppendBufferTask(already_AddRefed<MediaByteBuffer> aData,
                    const SourceBufferAttributes& aAttributes)
   : mBuffer(aData)
   , mAttributes(aAttributes)
   {}
 
   static const Type sType = Type::AppendBuffer;
   Type GetType() const override { return Type::AppendBuffer; }
 

--- a/dom/media/mediasource/TrackBuffersManager.cpp
+++ b/dom/media/mediasource/TrackBuffersManager.cpp
@@ -111,34 +111,34 @@ TrackBuffersManager::TrackBuffersManager
 }
 
 TrackBuffersManager::~TrackBuffersManager()
 {
   ShutdownDemuxers();
 }
 
 RefPtr<TrackBuffersManager::AppendPromise>
-TrackBuffersManager::AppendData(MediaByteBuffer* aData,
+TrackBuffersManager::AppendData(already_AddRefed<MediaByteBuffer> aData,
                                 const SourceBufferAttributes& aAttributes)
 {
   MOZ_ASSERT(NS_IsMainThread());
-  MSE_DEBUG("Appending %" PRIuSIZE " bytes", aData->Length());
+  RefPtr<MediaByteBuffer> data(aData);
+  MSE_DEBUG("Appending %" PRIuSIZE " bytes", data->Length());
 
   mEnded = false;
 
-  return InvokeAsync<RefPtr<MediaByteBuffer>, SourceBufferAttributes&&>(
-           GetTaskQueue(), this, __func__,
-           &TrackBuffersManager::DoAppendData, aData, aAttributes);
+  return InvokeAsync(GetTaskQueue(), this, __func__,
+    &TrackBuffersManager::DoAppendData, data.forget(), aAttributes);
 }
 
 RefPtr<TrackBuffersManager::AppendPromise>
-TrackBuffersManager::DoAppendData(MediaByteBuffer* aData,
+TrackBuffersManager::DoAppendData(already_AddRefed<MediaByteBuffer> aData,
                                   const SourceBufferAttributes& aAttributes)
 {
-  RefPtr<AppendBufferTask> task = new AppendBufferTask(aData, aAttributes);
+  RefPtr<AppendBufferTask> task = new AppendBufferTask(Move(aData), aAttributes);
   RefPtr<AppendPromise> p = task->mPromise.Ensure(__func__);
   QueueTask(task);
 
   return p;
 }
 
 void
 TrackBuffersManager::QueueTask(SourceBufferTask* aTask)

--- a/dom/media/mediasource/TrackBuffersManager.h
+++ b/dom/media/mediasource/TrackBuffersManager.h
@@ -93,17 +93,17 @@ public:
   // Interface for SourceBuffer
   TrackBuffersManager(MediaSourceDecoder* aParentDecoder,
                       const MediaContainerType& aType);
 
   // Queue a task to add data to the end of the input buffer and run the MSE
   // Buffer Append Algorithm
   // 3.5.5 Buffer Append Algorithm.
   // http://w3c.github.io/media-source/index.html#sourcebuffer-buffer-append
-  RefPtr<AppendPromise> AppendData(MediaByteBuffer* aData,
+  RefPtr<AppendPromise> AppendData(already_AddRefed<MediaByteBuffer> aData,
                                    const SourceBufferAttributes& aAttributes);
 
   // Queue a task to abort any pending AppendData.
   // Does nothing at this stage.
   void AbortAppendData();
 
   // Queue a task to run MSE Reset Parser State Algorithm.
   // 3.5.2 Reset Parser State
@@ -169,17 +169,17 @@ public:
 
 private:
   typedef MozPromise<bool, MediaResult, /* IsExclusive = */ true> CodedFrameProcessingPromise;
 
   // for MediaSourceDemuxer::GetMozDebugReaderData
   friend class MediaSourceDemuxer;
   ~TrackBuffersManager();
   // All following functions run on the taskqueue.
-  RefPtr<AppendPromise> DoAppendData(MediaByteBuffer* aData,
+  RefPtr<AppendPromise> DoAppendData(already_AddRefed<MediaByteBuffer> aData,
                                      const SourceBufferAttributes& aAttributes);
   void ScheduleSegmentParserLoop();
   void SegmentParserLoop();
   void InitializationSegmentReceived();
   void ShutdownDemuxers();
   void CreateDemuxerforMIMEType();
   void ResetDemuxingState();
   void NeedMoreData();