deleted file mode 100644
--- a/dom/media/AccurateSeekTask.cpp
+++ /dev/null
@@ -1,103 +0,0 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* vim:set ts=2 sw=2 sts=2 et cindent: */
-/* 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/. */
-
-#include "AccurateSeekTask.h"
-#include "MediaDecoderReaderWrapper.h"
-#include "mozilla/AbstractThread.h"
-#include "mozilla/Assertions.h"
-#include "nsPrintfCString.h"
-
-namespace mozilla {
-
-extern LazyLogModule gMediaDecoderLog;
-extern LazyLogModule gMediaSampleLog;
-
-// avoid redefined macro in unified build
-#undef FMT
-#undef DECODER_LOG
-#undef SAMPLE_LOG
-#undef DECODER_WARN
-
-#define FMT(x, ...) "[AccurateSeekTask] Decoder=%p " x, mDecoderID, ##__VA_ARGS__
-#define DECODER_LOG(...) MOZ_LOG(gMediaDecoderLog, LogLevel::Debug,   (FMT(__VA_ARGS__)))
-#define SAMPLE_LOG(...)  MOZ_LOG(gMediaSampleLog,  LogLevel::Debug,   (FMT(__VA_ARGS__)))
-#define DECODER_WARN(...) NS_WARNING(nsPrintfCString(FMT(__VA_ARGS__)).get())
-
-AccurateSeekTask::AccurateSeekTask(const void* aDecoderID,
-                                   AbstractThread* aThread,
-                                   MediaDecoderReaderWrapper* aReader,
-                                   const SeekTarget& aTarget,
-                                   const MediaInfo& aInfo,
-                                   const media::TimeUnit& aEnd,
-                                   int64_t aCurrentMediaTime)
-  : SeekTask(aDecoderID, aThread, aReader, aTarget)
-{
-  AssertOwnerThread();
-}
-
-AccurateSeekTask::~AccurateSeekTask()
-{
-  AssertOwnerThread();
-  MOZ_ASSERT(mIsDiscarded);
-}
-
-void
-AccurateSeekTask::Discard()
-{
-  AssertOwnerThread();
-
-  // Disconnect MDSM.
-  RejectIfExist(NS_ERROR_DOM_MEDIA_CANCELED, __func__);
-
-  mIsDiscarded = true;
-}
-
-int64_t
-AccurateSeekTask::CalculateNewCurrentTime() const
-{
-  AssertOwnerThread();
-  return 0;
-}
-
-void
-AccurateSeekTask::HandleAudioDecoded(MediaData* aAudio)
-{
-}
-
-void
-AccurateSeekTask::HandleVideoDecoded(MediaData* aVideo, TimeStamp aDecodeStart)
-{
-}
-
-void
-AccurateSeekTask::HandleNotDecoded(MediaData::Type aType, const MediaResult& aError)
-{
-}
-
-void
-AccurateSeekTask::HandleAudioWaited(MediaData::Type aType)
-{
-}
-
-void
-AccurateSeekTask::HandleVideoWaited(MediaData::Type aType)
-{
-}
-
-void
-AccurateSeekTask::HandleNotWaited(const WaitForDataRejectValue& aRejection)
-{
-}
-
-RefPtr<AccurateSeekTask::SeekTaskPromise>
-AccurateSeekTask::Seek(const media::TimeUnit& aDuration)
-{
-  AssertOwnerThread();
-
-  return mSeekTaskPromise.Ensure(__func__);
-}
-
-} // namespace mozilla

deleted file mode 100644
--- a/dom/media/AccurateSeekTask.h
+++ /dev/null
@@ -1,49 +0,0 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* 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 ACCURATE_SEEK_TASK_H
-#define ACCURATE_SEEK_TASK_H
-
-#include "SeekTask.h"
-#include "MediaDecoderReader.h"
-#include "SeekJob.h"
-
-namespace mozilla {
-
-class AccurateSeekTask final : public SeekTask {
-public:
-  AccurateSeekTask(const void* aDecoderID,
-                   AbstractThread* aThread,
-                   MediaDecoderReaderWrapper* aReader,
-                   const SeekTarget& aTarget,
-                   const MediaInfo& aInfo,
-                   const media::TimeUnit& aEnd,
-                   int64_t aCurrentMediaTime);
-
-  void Discard() override;
-
-  RefPtr<SeekTaskPromise> Seek(const media::TimeUnit& aDuration) override;
-
-  int64_t CalculateNewCurrentTime() const override;
-
-  void HandleAudioDecoded(MediaData* aAudio) override;
-
-  void HandleVideoDecoded(MediaData* aVideo, TimeStamp aDecodeStart) override;
-
-  void HandleNotDecoded(MediaData::Type aType, const MediaResult& aError) override;
-
-  void HandleAudioWaited(MediaData::Type aType) override;
-
-  void HandleVideoWaited(MediaData::Type aType) override;
-
-  void HandleNotWaited(const WaitForDataRejectValue& aRejection) override;
-
-  ~AccurateSeekTask();
-};
-
-} // namespace mozilla
-
-#endif /* ACCURATE_SEEK_TASK_H */

--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -32,17 +32,16 @@
 #include "nsContentUtils.h"
 #include "nsIEventTarget.h"
 #include "nsITimer.h"
 #include "nsPrintfCString.h"
 #include "nsTArray.h"
 #include "nsDeque.h"
 #include "prenv.h"
 
-#include "AccurateSeekTask.h"
 #include "AudioSegment.h"
 #include "DOMMediaStream.h"
 #include "ImageContainer.h"
 #include "MediaDecoder.h"
 #include "MediaDecoderReader.h"
 #include "MediaDecoderReaderWrapper.h"
 #include "MediaDecoderStateMachine.h"
 #include "MediaShutdownManager.h"
@@ -1326,20 +1325,16 @@ private:
 
   /*
    * Information which are going to be returned to MDSM.
    */
   RefPtr<MediaData> mSeekedAudioData;
   RefPtr<MediaData> mSeekedVideoData;
   bool mIsAudioQueueFinished = false;
   bool mIsVideoQueueFinished = false;
-
-  // For refactoring only, will be removed later.
-  RefPtr<AccurateSeekTask> mTask;
-
 };
 
 class MediaDecoderStateMachine::NextFrameSeekingState
   : public MediaDecoderStateMachine::SeekingState
 {
 public:
   explicit NextFrameSeekingState(Master* aPtr) : SeekingState(aPtr)
   {

--- a/dom/media/moz.build
+++ b/dom/media/moz.build
@@ -72,17 +72,16 @@ XPIDL_SOURCES += [
     'nsIDOMNavigatorUserMedia.idl',
     'nsIMediaManager.idl',
 ]
 
 XPIDL_MODULE = 'dom_media'
 
 EXPORTS += [
     'AbstractMediaDecoder.h',
-    'AccurateSeekTask.h',
     'ADTSDecoder.h',
     'ADTSDemuxer.h',
     'AudioBufferUtils.h',
     'AudioChannelFormat.h',
     'AudioCompactor.h',
     'AudioConverter.h',
     'AudioMixer.h',
     'AudioPacketizer.h',
@@ -183,17 +182,16 @@ EXPORTS.mozilla.dom += [
     'TextTrackRegion.h',
     'VideoPlaybackQuality.h',
     'VideoStreamTrack.h',
     'VideoTrack.h',
     'VideoTrackList.h',
 ]
 
 UNIFIED_SOURCES += [
-    'AccurateSeekTask.cpp',
     'ADTSDecoder.cpp',
     'ADTSDemuxer.cpp',
     'AudioCaptureStream.cpp',
     'AudioChannelFormat.cpp',
     'AudioCompactor.cpp',
     'AudioConverter.cpp',
     'AudioSegment.cpp',
     'AudioStream.cpp',