diff --git a/dom/media/DecoderTraits.cpp b/dom/media/DecoderTraits.cpp
index b63da266da9..5093be06c1b 100644
--- a/dom/media/DecoderTraits.cpp
+++ b/dom/media/DecoderTraits.cpp
@@ -17,7 +17,6 @@
 #include "WaveReader.h"
 
 #include "WebMDecoder.h"
-#include "WebMReader.h"
 #include "WebMDemuxer.h"
 
 #ifdef MOZ_RAW
@@ -639,13 +638,10 @@ MediaDecoderReader* DecoderTraits::CreateReader(const nsACString& aType, Abstrac
     decoderReader = new AndroidMediaReader(aDecoder, aType);
   } else
 #endif
-
   if (IsWebMSupportedType(aType)) {
-    decoderReader = Preferences::GetBool("media.format-reader.webm", true) ?
-      static_cast<MediaDecoderReader*>(new MediaFormatReader(aDecoder, new WebMDemuxer(aDecoder->GetResource()))) :
-      new WebMReader(aDecoder);
+    decoderReader =
+      new MediaFormatReader(aDecoder, new WebMDemuxer(aDecoder->GetResource()));
   } else
-
 #ifdef MOZ_DIRECTSHOW
   if (IsDirectShowSupportedType(aType)) {
     decoderReader = new DirectShowReader(aDecoder);
diff --git a/dom/media/webm/AudioDecoder.cpp b/dom/media/webm/AudioDecoder.cpp
deleted file mode 100644
index cd2bd034231..00000000000
--- a/dom/media/webm/AudioDecoder.cpp
+++ /dev/null
@@ -1,472 +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 "WebMReader.h"
-
-#ifdef MOZ_TREMOR
-#include "tremor/ivorbiscodec.h"
-#else
-#include "vorbis/codec.h"
-#endif
-
-#include "OpusParser.h"
-
-#include "VorbisUtils.h"
-#include "OggReader.h"
-
-#undef LOG
-
-#ifdef PR_LOGGING
-#include "prprf.h"
-#define LOG(type, msg) MOZ_LOG(gMediaDecoderLog, type, msg)
-#else
-#define LOG(type, msg)
-#endif
-
-namespace mozilla {
-
-extern LazyLogModule gMediaDecoderLog;
-
-ogg_packet InitOggPacket(const unsigned char* aData, size_t aLength,
-                         bool aBOS, bool aEOS,
-                         int64_t aGranulepos, int64_t aPacketNo)
-{
-  ogg_packet packet;
-  packet.packet = const_cast<unsigned char*>(aData);
-  packet.bytes = aLength;
-  packet.b_o_s = aBOS;
-  packet.e_o_s = aEOS;
-  packet.granulepos = aGranulepos;
-  packet.packetno = aPacketNo;
-  return packet;
-}
-
-class VorbisDecoder : public WebMAudioDecoder
-{
-public:
-  nsresult Init() override;
-  void Shutdown() override;
-  nsresult ResetDecode() override;
-  nsresult DecodeHeader(const unsigned char* aData, size_t aLength) override;
-  nsresult FinishInit(AudioInfo& aInfo) override;
-  bool Decode(const unsigned char* aData, size_t aLength,
-              int64_t aOffset, uint64_t aTstampUsecs,
-              int64_t aDiscardPadding, int32_t* aTotalFrames) override;
-  explicit VorbisDecoder(WebMReader* aReader);
-  ~VorbisDecoder();
-private:
-  RefPtr<WebMReader> mReader;
-
-  // Vorbis decoder state
-  vorbis_info mVorbisInfo;
-  vorbis_comment mVorbisComment;
-  vorbis_dsp_state mVorbisDsp;
-  vorbis_block mVorbisBlock;
-  int64_t mPacketCount;
-};
-
-VorbisDecoder::VorbisDecoder(WebMReader* aReader)
-  : mReader(aReader)
-  , mPacketCount(0)
-{
-  // Zero these member vars to avoid crashes in Vorbis clear functions when
-  // destructor is called before |Init|.
-  PodZero(&mVorbisBlock);
-  PodZero(&mVorbisDsp);
-  PodZero(&mVorbisInfo);
-  PodZero(&mVorbisComment);
-}
-
-VorbisDecoder::~VorbisDecoder()
-{
-  vorbis_block_clear(&mVorbisBlock);
-  vorbis_dsp_clear(&mVorbisDsp);
-  vorbis_info_clear(&mVorbisInfo);
-  vorbis_comment_clear(&mVorbisComment);
-}
-
-void
-VorbisDecoder::Shutdown()
-{
-  mReader = nullptr;
-}
-
-nsresult
-VorbisDecoder::Init()
-{
-  vorbis_info_init(&mVorbisInfo);
-  vorbis_comment_init(&mVorbisComment);
-  PodZero(&mVorbisDsp);
-  PodZero(&mVorbisBlock);
-  return NS_OK;
-}
-
-nsresult
-VorbisDecoder::ResetDecode()
-{
-  // Ignore failed results from vorbis_synthesis_restart. They
-  // aren't fatal and it fails when ResetDecode is called at a
-  // time when no vorbis data has been read.
-  vorbis_synthesis_restart(&mVorbisDsp);
-  return NS_OK;
-}
-
-nsresult
-VorbisDecoder::DecodeHeader(const unsigned char* aData, size_t aLength)
-{
-  bool bos = mPacketCount == 0;
-  ogg_packet pkt = InitOggPacket(aData, aLength, bos, false, 0, mPacketCount++);
-  MOZ_ASSERT(mPacketCount <= 3);
-
-  int r = vorbis_synthesis_headerin(&mVorbisInfo,
-                                    &mVorbisComment,
-                                    &pkt);
-  return r == 0 ? NS_OK : NS_ERROR_FAILURE;
-}
-
-nsresult
-VorbisDecoder::FinishInit(AudioInfo& aInfo)
-{
-  MOZ_ASSERT(mPacketCount == 3);
-
-  int r = vorbis_synthesis_init(&mVorbisDsp, &mVorbisInfo);
-  if (r) {
-    return NS_ERROR_FAILURE;
-  }
-
-  r = vorbis_block_init(&mVorbisDsp, &mVorbisBlock);
-  if (r) {
-    return NS_ERROR_FAILURE;
-  }
-
-  aInfo.mRate = mVorbisDsp.vi->rate;
-  aInfo.mChannels = mVorbisDsp.vi->channels;
-
-  return NS_OK;
-}
-
-bool
-VorbisDecoder::Decode(const unsigned char* aData, size_t aLength,
-                      int64_t aOffset, uint64_t aTstampUsecs,
-                      int64_t aDiscardPadding, int32_t* aTotalFrames)
-{
-  MOZ_ASSERT(mPacketCount >= 3);
-  ogg_packet pkt = InitOggPacket(aData, aLength, false, false, -1, mPacketCount++);
-  bool first_packet = mPacketCount == 4;
-
-  if (vorbis_synthesis(&mVorbisBlock, &pkt)) {
-    return false;
-  }
-
-  if (vorbis_synthesis_blockin(&mVorbisDsp,
-                               &mVorbisBlock)) {
-    return false;
-  }
-
-  VorbisPCMValue** pcm = 0;
-  int32_t frames = vorbis_synthesis_pcmout(&mVorbisDsp, &pcm);
-  // If the first packet of audio in the media produces no data, we
-  // still need to produce an AudioData for it so that the correct media
-  // start time is calculated.  Otherwise we'd end up with a media start
-  // time derived from the timecode of the first packet that produced
-  // data.
-  if (frames == 0 && first_packet) {
-    mReader->AudioQueue().Push(new AudioData(aOffset, aTstampUsecs, 0, 0, nullptr,
-                                             mVorbisDsp.vi->channels,
-                                             mVorbisDsp.vi->rate));
-  }
-  while (frames > 0) {
-    uint32_t channels = mVorbisDsp.vi->channels;
-    auto buffer = MakeUnique<AudioDataValue[]>(frames*channels);
-    for (uint32_t j = 0; j < channels; ++j) {
-      VorbisPCMValue* channel = pcm[j];
-      for (uint32_t i = 0; i < uint32_t(frames); ++i) {
-        buffer[i*channels + j] = MOZ_CONVERT_VORBIS_SAMPLE(channel[i]);
-      }
-    }
-
-    CheckedInt64 duration = FramesToUsecs(frames, mVorbisDsp.vi->rate);
-    if (!duration.isValid()) {
-      NS_WARNING("Int overflow converting WebM audio duration");
-      return false;
-    }
-    CheckedInt64 total_duration = FramesToUsecs(*aTotalFrames,
-                                                mVorbisDsp.vi->rate);
-    if (!total_duration.isValid()) {
-      NS_WARNING("Int overflow converting WebM audio total_duration");
-      return false;
-    }
-
-    CheckedInt64 time = total_duration + aTstampUsecs;
-    if (!time.isValid()) {
-      NS_WARNING("Int overflow adding total_duration and aTstampUsecs");
-      return false;
-    };
-
-    *aTotalFrames += frames;
-    mReader->AudioQueue().Push(new AudioData(aOffset,
-                                             time.value(),
-                                             duration.value(),
-                                             frames,
-                                             Move(buffer),
-                                             mVorbisDsp.vi->channels,
-                                             mVorbisDsp.vi->rate));
-    if (vorbis_synthesis_read(&mVorbisDsp, frames)) {
-      return false;
-    }
-
-    frames = vorbis_synthesis_pcmout(&mVorbisDsp, &pcm);
-  }
-
-  return true;
-}
-
-// ------------------------------------------------------------------------
-
-class OpusDecoder : public WebMAudioDecoder
-{
-public:
-  nsresult Init() override;
-  void Shutdown() override;
-  nsresult ResetDecode() override;
-  nsresult DecodeHeader(const unsigned char* aData, size_t aLength) override;
-  nsresult FinishInit(AudioInfo& aInfo) override;
-  bool Decode(const unsigned char* aData, size_t aLength,
-              int64_t aOffset, uint64_t aTstampUsecs,
-              int64_t aDiscardPadding, int32_t* aTotalFrames) override;
-  explicit OpusDecoder(WebMReader* aReader);
-  ~OpusDecoder();
-private:
-  RefPtr<WebMReader> mReader;
-
-  // Opus decoder state
-  nsAutoPtr<OpusParser> mOpusParser;
-  OpusMSDecoder* mOpusDecoder;
-  uint16_t mSkip;        // Samples left to trim before playback.
-  bool mDecodedHeader;
-
-  // Opus padding should only be discarded on the final packet.  Once this
-  // is set to true, if the reader attempts to decode any further packets it
-  // will raise an error so we can indicate that the file is invalid.
-  bool mPaddingDiscarded;
-};
-
-OpusDecoder::OpusDecoder(WebMReader* aReader)
-  : mReader(aReader)
-  , mOpusDecoder(nullptr)
-  , mSkip(0)
-  , mDecodedHeader(false)
-  , mPaddingDiscarded(false)
-{
-}
-
-OpusDecoder::~OpusDecoder()
-{
-  if (mOpusDecoder) {
-    opus_multistream_decoder_destroy(mOpusDecoder);
-    mOpusDecoder = nullptr;
-  }
-}
-
-void
-OpusDecoder::Shutdown()
-{
-  mReader = nullptr;
-}
-
-nsresult
-OpusDecoder::Init()
-{
-  return NS_OK;
-}
-
-nsresult
-OpusDecoder::ResetDecode()
-{
-  if (mOpusDecoder) {
-    // Reset the decoder.
-    opus_multistream_decoder_ctl(mOpusDecoder, OPUS_RESET_STATE);
-    mSkip = mOpusParser->mPreSkip;
-    mPaddingDiscarded = false;
-  }
-  return NS_OK;
-}
-
-nsresult
-OpusDecoder::DecodeHeader(const unsigned char* aData, size_t aLength)
-{
-  MOZ_ASSERT(!mOpusParser);
-  MOZ_ASSERT(!mOpusDecoder);
-  MOZ_ASSERT(!mDecodedHeader);
-  mDecodedHeader = true;
-
-  mOpusParser = new OpusParser;
-  if (!mOpusParser->DecodeHeader(const_cast<unsigned char*>(aData), aLength)) {
-    return NS_ERROR_FAILURE;
-  }
-
-  return NS_OK;
-}
-
-nsresult
-OpusDecoder::FinishInit(AudioInfo& aInfo)
-{
-  MOZ_ASSERT(mDecodedHeader);
-
-  int r;
-  mOpusDecoder = opus_multistream_decoder_create(mOpusParser->mRate,
-                                                 mOpusParser->mChannels,
-                                                 mOpusParser->mStreams,
-                                                 mOpusParser->mCoupledStreams,
-                                                 mOpusParser->mMappingTable,
-                                                 &r);
-  mSkip = mOpusParser->mPreSkip;
-  mPaddingDiscarded = false;
-
-  if (int64_t(mReader->GetCodecDelay()) != FramesToUsecs(mOpusParser->mPreSkip,
-                                                         mOpusParser->mRate).value()) {
-    LOG(LogLevel::Warning,
-        ("Invalid Opus header: CodecDelay and pre-skip do not match!"));
-    return NS_ERROR_FAILURE;
-  }
-
-  aInfo.mRate = mOpusParser->mRate;
-  aInfo.mChannels = mOpusParser->mChannels;
-
-  return r == OPUS_OK ? NS_OK : NS_ERROR_FAILURE;
-}
-
-bool
-OpusDecoder::Decode(const unsigned char* aData, size_t aLength,
-                    int64_t aOffset, uint64_t aTstampUsecs,
-                    int64_t aDiscardPadding, int32_t* aTotalFrames)
-{
-  uint32_t channels = mOpusParser->mChannels;
-  // No channel mapping for more than 8 channels.
-  if (channels > 8) {
-    return false;
-  }
-
-  if (mPaddingDiscarded) {
-    // Discard padding should be used only on the final packet, so
-    // decoding after a padding discard is invalid.
-    LOG(LogLevel::Debug, ("Opus error, discard padding on interstitial packet"));
-    return false;
-  }
-
-  // Maximum value is 63*2880, so there's no chance of overflow.
-  int32_t frames_number = opus_packet_get_nb_frames(aData, aLength);
-  if (frames_number <= 0) {
-    return false; // Invalid packet header.
-  }
-
-  int32_t samples =
-    opus_packet_get_samples_per_frame(aData, opus_int32(mOpusParser->mRate));
-
-  // A valid Opus packet must be between 2.5 and 120 ms long (48kHz).
-  int32_t frames = frames_number*samples;
-  if (frames < 120 || frames > 5760)
-    return false;
-
-  auto buffer = MakeUnique<AudioDataValue[]>(frames * channels);
-
-  // Decode to the appropriate sample type.
-#ifdef MOZ_SAMPLE_TYPE_FLOAT32
-  int ret = opus_multistream_decode_float(mOpusDecoder,
-                                          aData, aLength,
-                                          buffer.get(), frames, false);
-#else
-  int ret = opus_multistream_decode(mOpusDecoder,
-                                    aData, aLength,
-                                    buffer.get(), frames, false);
-#endif
-  if (ret < 0)
-    return false;
-  NS_ASSERTION(ret == frames, "Opus decoded too few audio samples");
-  CheckedInt64 startTime = aTstampUsecs;
-
-  // Trim the initial frames while the decoder is settling.
-  if (mSkip > 0) {
-    int32_t skipFrames = std::min<int32_t>(mSkip, frames);
-    int32_t keepFrames = frames - skipFrames;
-    LOG(LogLevel::Debug, ("Opus decoder skipping %d of %d frames",
-                       skipFrames, frames));
-    PodMove(buffer.get(),
-            buffer.get() + skipFrames * channels,
-            keepFrames * channels);
-    startTime = startTime + FramesToUsecs(skipFrames, mOpusParser->mRate);
-    frames = keepFrames;
-    mSkip -= skipFrames;
-  }
-
-  if (aDiscardPadding < 0) {
-    // Negative discard padding is invalid.
-    LOG(LogLevel::Debug, ("Opus error, negative discard padding"));
-    return false;
-  }
-  if (aDiscardPadding > 0) {
-    CheckedInt64 discardFrames = UsecsToFrames(aDiscardPadding / NS_PER_USEC,
-                                               mOpusParser->mRate);
-    if (!discardFrames.isValid()) {
-      NS_WARNING("Int overflow in DiscardPadding");
-      return false;
-    }
-    if (discardFrames.value() > frames) {
-      // Discarding more than the entire packet is invalid.
-      LOG(LogLevel::Debug, ("Opus error, discard padding larger than packet"));
-      return false;
-    }
-    LOG(LogLevel::Debug, ("Opus decoder discarding %d of %d frames",
-                       int32_t(discardFrames.value()), frames));
-    // Padding discard is only supposed to happen on the final packet.
-    // Record the discard so we can return an error if another packet is
-    // decoded.
-    mPaddingDiscarded = true;
-    int32_t keepFrames = frames - discardFrames.value();
-    frames = keepFrames;
-  }
-
-  // Apply the header gain if one was specified.
-#ifdef MOZ_SAMPLE_TYPE_FLOAT32
-  if (mOpusParser->mGain != 1.0f) {
-    float gain = mOpusParser->mGain;
-    int samples = frames * channels;
-    for (int i = 0; i < samples; i++) {
-      buffer[i] *= gain;
-    }
-  }
-#else
-  if (mOpusParser->mGain_Q16 != 65536) {
-    int64_t gain_Q16 = mOpusParser->mGain_Q16;
-    int samples = frames * channels;
-    for (int i = 0; i < samples; i++) {
-      int32_t val = static_cast<int32_t>((gain_Q16*buffer[i] + 32768)>>16);
-      buffer[i] = static_cast<AudioDataValue>(MOZ_CLIP_TO_15(val));
-    }
-  }
-#endif
-
-  CheckedInt64 duration = FramesToUsecs(frames, mOpusParser->mRate);
-  if (!duration.isValid()) {
-    NS_WARNING("Int overflow converting WebM audio duration");
-    return false;
-  }
-  CheckedInt64 time = startTime - mReader->GetCodecDelay();
-  if (!time.isValid()) {
-    NS_WARNING("Int overflow shifting tstamp by codec delay");
-    return false;
-  };
-  mReader->AudioQueue().Push(new AudioData(aOffset,
-                                           time.value(),
-                                           duration.value(),
-                                           frames,
-                                           Move(buffer),
-                                           mOpusParser->mChannels,
-                                           mOpusParser->mRate));
-  return true;
-}
-
-} // namespace mozilla
diff --git a/dom/media/webm/EbmlComposer.cpp b/dom/media/webm/EbmlComposer.cpp
index 1bda401e09c..a0a0ddf8776 100644
--- a/dom/media/webm/EbmlComposer.cpp
+++ b/dom/media/webm/EbmlComposer.cpp
@@ -4,6 +4,7 @@
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "EbmlComposer.h"
+#include "mozilla/UniquePtr.h"
 #include "libmkv/EbmlIDs.h"
 #include "libmkv/EbmlWriter.h"
 #include "libmkv/WebMElement.h"
@@ -22,7 +23,7 @@ void EbmlComposer::GenerateHeader()
   EbmlGlobal ebml;
   // The WEbM header default size usually smaller than 1k.
   auto buffer = MakeUnique<uint8_t[]>(DEFAULT_HEADER_SIZE +
-                                             mCodecPrivateData.Length());
+                                      mCodecPrivateData.Length());
   ebml.buf = buffer.get();
   ebml.offset = 0;
   writeHeader(&ebml);
diff --git a/dom/media/webm/SoftwareWebMVideoDecoder.cpp b/dom/media/webm/SoftwareWebMVideoDecoder.cpp
deleted file mode 100644
index d63e24c7341..00000000000
--- a/dom/media/webm/SoftwareWebMVideoDecoder.cpp
+++ /dev/null
@@ -1,233 +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 "SoftwareWebMVideoDecoder.h"
-#include "AbstractMediaDecoder.h"
-#include "gfx2DGlue.h"
-#include "MediaDecoderStateMachine.h"
-#include "MediaResource.h"
-#include "nsError.h"
-#include "OggReader.h"
-#include "TimeUnits.h"
-#include "VorbisUtils.h"
-#include "WebMBufferedParser.h"
-#include "NesteggPacketHolder.h"
-
-#include <algorithm>
-
-#define VPX_DONT_DEFINE_STDINT_TYPES
-#include "vpx/vp8dx.h"
-#include "vpx/vpx_decoder.h"
-
-namespace mozilla {
-
-using namespace gfx;
-using namespace layers;
-
-SoftwareWebMVideoDecoder::SoftwareWebMVideoDecoder(WebMReader* aReader)
-  : WebMVideoDecoder(),
-    mReader(aReader)
-{
-  MOZ_COUNT_CTOR(SoftwareWebMVideoDecoder);
-  PodZero(&mVPX);
-}
-
-SoftwareWebMVideoDecoder::~SoftwareWebMVideoDecoder()
-{
-  MOZ_COUNT_DTOR(SoftwareWebMVideoDecoder);
-}
-
-void
-SoftwareWebMVideoDecoder::Shutdown()
-{
-  vpx_codec_destroy(&mVPX);
-  mReader = nullptr;
-}
-
-/* static */
-WebMVideoDecoder*
-SoftwareWebMVideoDecoder::Create(WebMReader* aReader)
-{
-  return new SoftwareWebMVideoDecoder(aReader);
-}
-
-nsresult
-SoftwareWebMVideoDecoder::Init(unsigned int aWidth, unsigned int aHeight)
-{
-  return InitDecoder(aWidth, aHeight);
-}
-
-nsresult
-SoftwareWebMVideoDecoder::InitDecoder(unsigned int aWidth, unsigned int aHeight)
-{
-  vpx_codec_iface_t* dx = nullptr;
-  switch(mReader->GetVideoCodec()) {
-    case NESTEGG_CODEC_VP8:
-      dx = vpx_codec_vp8_dx();
-      break;
-    case NESTEGG_CODEC_VP9:
-      dx = vpx_codec_vp9_dx();
-      break;
-  }
-  if (!dx || vpx_codec_dec_init(&mVPX, dx, nullptr, 0)) {
-    return NS_ERROR_FAILURE;
-  }
-  return NS_OK;
-}
-
-bool
-SoftwareWebMVideoDecoder::DecodeVideoFrame(bool &aKeyframeSkip,
-                                           int64_t aTimeThreshold)
-{
-  MOZ_ASSERT(mReader->OnTaskQueue());
-
-  // Record number of frames decoded and parsed. Automatically update the
-  // stats counters using the AutoNotifyDecoded stack-based class.
-  AbstractMediaDecoder::AutoNotifyDecoded a(mReader->GetDecoder());
-
-  RefPtr<NesteggPacketHolder> holder(mReader->NextPacket(WebMReader::VIDEO));
-  if (!holder) {
-    return false;
-  }
-
-  nestegg_packet* packet = holder->Packet();
-  unsigned int track = 0;
-  int r = nestegg_packet_track(packet, &track);
-  if (r == -1) {
-    return false;
-  }
-
-  unsigned int count = 0;
-  r = nestegg_packet_count(packet, &count);
-  if (r == -1) {
-    return false;
-  }
-
-  if (count > 1) {
-    NS_WARNING("Packet contains more than one video frame");
-    return false;
-  }
-
-  int64_t tstamp = holder->Timestamp();
-
-  // The end time of this frame is the start time of the next frame.  Fetch
-  // the timestamp of the next packet for this track.  If we've reached the
-  // end of the resource, use the file's duration as the end time of this
-  // video frame.
-  int64_t next_tstamp = 0;
-  RefPtr<NesteggPacketHolder> next_holder(mReader->NextPacket(WebMReader::VIDEO));
-  if (next_holder) {
-    next_tstamp = next_holder->Timestamp();
-    mReader->PushVideoPacket(next_holder);
-  } else {
-    next_tstamp = tstamp;
-    next_tstamp += tstamp - mReader->GetLastVideoFrameTime();
-  }
-  mReader->SetLastVideoFrameTime(tstamp);
-
-  unsigned char* data;
-  size_t length;
-  r = nestegg_packet_data(packet, 0, &data, &length);
-  if (r == -1) {
-    return false;
-  }
-
-  vpx_codec_stream_info_t si;
-  PodZero(&si);
-  si.sz = sizeof(si);
-  if (mReader->GetVideoCodec() == NESTEGG_CODEC_VP8) {
-    vpx_codec_peek_stream_info(vpx_codec_vp8_dx(), data, length, &si);
-  } else if (mReader->GetVideoCodec() == NESTEGG_CODEC_VP9) {
-    vpx_codec_peek_stream_info(vpx_codec_vp9_dx(), data, length, &si);
-  }
-  if (aKeyframeSkip && (!si.is_kf || tstamp < aTimeThreshold)) {
-    // Skipping to next keyframe...
-    a.mParsed++;
-    a.mDropped++;
-    return true;
-  }
-
-  if (aKeyframeSkip && si.is_kf) {
-    aKeyframeSkip = false;
-  }
-
-  if (vpx_codec_decode(&mVPX, data, length, nullptr, 0)) {
-    return false;
-  }
-
-  // If the timestamp of the video frame is less than
-  // the time threshold required then it is not added
-  // to the video queue and won't be displayed.
-  if (tstamp < aTimeThreshold) {
-    a.mParsed++;
-    a.mDropped++;
-    return true;
-  }
-
-  vpx_codec_iter_t  iter = nullptr;
-  vpx_image_t      *img;
-
-  while ((img = vpx_codec_get_frame(&mVPX, &iter))) {
-    NS_ASSERTION(img->fmt == VPX_IMG_FMT_I420, "WebM image format not I420");
-
-    // Chroma shifts are rounded down as per the decoding examples in the SDK
-    VideoData::YCbCrBuffer b;
-    b.mPlanes[0].mData = img->planes[0];
-    b.mPlanes[0].mStride = img->stride[0];
-    b.mPlanes[0].mHeight = img->d_h;
-    b.mPlanes[0].mWidth = img->d_w;
-    b.mPlanes[0].mOffset = b.mPlanes[0].mSkip = 0;
-
-    b.mPlanes[1].mData = img->planes[1];
-    b.mPlanes[1].mStride = img->stride[1];
-    b.mPlanes[1].mHeight = (img->d_h + 1) >> img->y_chroma_shift;
-    b.mPlanes[1].mWidth = (img->d_w + 1) >> img->x_chroma_shift;
-    b.mPlanes[1].mOffset = b.mPlanes[1].mSkip = 0;
-
-    b.mPlanes[2].mData = img->planes[2];
-    b.mPlanes[2].mStride = img->stride[2];
-    b.mPlanes[2].mHeight = (img->d_h + 1) >> img->y_chroma_shift;
-    b.mPlanes[2].mWidth = (img->d_w + 1) >> img->x_chroma_shift;
-    b.mPlanes[2].mOffset = b.mPlanes[2].mSkip = 0;
-
-    nsIntRect pictureRect = mReader->GetPicture();
-    IntRect picture = pictureRect;
-    nsIntSize initFrame = mReader->GetInitialFrame();
-    if (img->d_w != static_cast<uint32_t>(initFrame.width) ||
-        img->d_h != static_cast<uint32_t>(initFrame.height)) {
-      // Frame size is different from what the container reports. This is
-      // legal in WebM, and we will preserve the ratio of the crop rectangle
-      // as it was reported relative to the picture size reported by the
-      // container.
-      picture.x = (pictureRect.x * img->d_w) / initFrame.width;
-      picture.y = (pictureRect.y * img->d_h) / initFrame.height;
-      picture.width = (img->d_w * pictureRect.width) / initFrame.width;
-      picture.height = (img->d_h * pictureRect.height) / initFrame.height;
-    }
-
-    VideoInfo videoInfo = mReader->GetMediaInfo().mVideo;
-    RefPtr<VideoData> v = VideoData::Create(videoInfo,
-                                              mReader->GetDecoder()->GetImageContainer(),
-                                              holder->Offset(),
-                                              tstamp,
-                                              next_tstamp - tstamp,
-                                              b,
-                                              si.is_kf,
-                                              -1,
-                                              picture);
-    if (!v) {
-      return false;
-    }
-    a.mParsed++;
-    a.mDecoded++;
-    NS_ASSERTION(a.mDecoded <= a.mParsed,
-                 "Expect only 1 frame per chunk per packet in WebM...");
-    mReader->VideoQueue().Push(v);
-  }
-
-  return true;
-}
-
-} // namespace mozilla
diff --git a/dom/media/webm/SoftwareWebMVideoDecoder.h b/dom/media/webm/SoftwareWebMVideoDecoder.h
deleted file mode 100644
index 52ff85b625e..00000000000
--- a/dom/media/webm/SoftwareWebMVideoDecoder.h
+++ /dev/null
@@ -1,41 +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/. */
-#if !defined(SoftwareWebMVideoDecoder_h_)
-#define SoftwareWebMVideoDecoder_h_
-
-#include <stdint.h>
-
-#include "WebMReader.h"
-
-namespace mozilla {
-
-class SoftwareWebMVideoDecoder : public WebMVideoDecoder
-{
-public:
-  static WebMVideoDecoder* Create(WebMReader* aReader);
-
-  virtual nsresult Init(unsigned int aWidth = 0,
-                        unsigned int aHeight = 0) override;
-
-  virtual bool DecodeVideoFrame(bool &aKeyframeSkip,
-                                int64_t aTimeThreshold) override;
-
-  virtual void Shutdown() override;
-
-  explicit SoftwareWebMVideoDecoder(WebMReader* aReader);
-  ~SoftwareWebMVideoDecoder();
-
-private:
-  nsresult InitDecoder(unsigned int aWidth, unsigned int aHeight);
-  RefPtr<WebMReader> mReader;
-
-  // VPx decoder state
-  vpx_codec_ctx_t mVPX;
-};
-
-} // namespace mozilla
-
-#endif
diff --git a/dom/media/webm/WebMDecoder.cpp b/dom/media/webm/WebMDecoder.cpp
index 8156f14fda3..fdc4f429c4b 100644
--- a/dom/media/webm/WebMDecoder.cpp
+++ b/dom/media/webm/WebMDecoder.cpp
@@ -8,7 +8,6 @@
 #include "MediaDecoderStateMachine.h"
 #include "MediaFormatReader.h"
 #include "WebMDemuxer.h"
-#include "WebMReader.h"
 #include "WebMDecoder.h"
 #include "VideoUtils.h"
 
@@ -16,11 +15,8 @@ namespace mozilla {
 
 MediaDecoderStateMachine* WebMDecoder::CreateStateMachine()
 {
-  bool useFormatDecoder =
-    Preferences::GetBool("media.format-reader.webm", true);
-  RefPtr<MediaDecoderReader> reader = useFormatDecoder ?
-      static_cast<MediaDecoderReader*>(new MediaFormatReader(this, new WebMDemuxer(GetResource()), GetVideoFrameContainer())) :
-      new WebMReader(this);
+  RefPtr<MediaDecoderReader> reader =
+    new MediaFormatReader(this, new WebMDemuxer(GetResource()), GetVideoFrameContainer());
   return new MediaDecoderStateMachine(this, reader);
 }
 
diff --git a/dom/media/webm/WebMDemuxer.cpp b/dom/media/webm/WebMDemuxer.cpp
index 1d3d6e36cc3..4cf3fe57d42 100644
--- a/dom/media/webm/WebMDemuxer.cpp
+++ b/dom/media/webm/WebMDemuxer.cpp
@@ -34,7 +34,7 @@ namespace mozilla {
 using namespace gfx;
 
 LazyLogModule gWebMDemuxerLog("WebMDemuxer");
-extern LazyLogModule gNesteggLog;
+LazyLogModule gNesteggLog("Nestegg");
 
 // How far ahead will we look when searching future keyframe. In microseconds.
 // This value is based on what appears to be a reasonable value as most webm
diff --git a/dom/media/webm/WebMReader.cpp b/dom/media/webm/WebMReader.cpp
deleted file mode 100644
index 3897e5cbc08..00000000000
--- a/dom/media/webm/WebMReader.cpp
+++ /dev/null
@@ -1,828 +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 "nsError.h"
-#include "MediaDecoderStateMachine.h"
-#include "AbstractMediaDecoder.h"
-#include "SoftwareWebMVideoDecoder.h"
-#include "nsContentUtils.h"
-#include "WebMReader.h"
-#include "WebMBufferedParser.h"
-#include "gfx2DGlue.h"
-#include "Layers.h"
-#include "mozilla/Preferences.h"
-#include "mozilla/SharedThreadPool.h"
-
-#include <algorithm>
-
-#define VPX_DONT_DEFINE_STDINT_TYPES
-#include "vpx/vp8dx.h"
-#include "vpx/vpx_decoder.h"
-
-// Un-comment to enable logging of seek bisections.
-//#define SEEK_LOGGING
-
-#undef LOG
-
-#include "prprf.h"
-#define LOG(type, msg) MOZ_LOG(gMediaDecoderLog, type, msg)
-#ifdef SEEK_LOGGING
-#define SEEK_LOG(type, msg) MOZ_LOG(gMediaDecoderLog, type, msg)
-#else
-#define SEEK_LOG(type, msg)
-#endif
-
-namespace mozilla {
-
-using namespace gfx;
-using namespace layers;
-using namespace media;
-
-extern LazyLogModule gMediaDecoderLog;
-LazyLogModule gNesteggLog("Nestegg");
-
-// Functions for reading and seeking using MediaResource required for
-// nestegg_io. The 'user data' passed to these functions is the
-// decoder from which the media resource is obtained.
-static int webm_read(void *aBuffer, size_t aLength, void *aUserData)
-{
-  MOZ_ASSERT(aUserData);
-  MediaResourceIndex* resource =
-    reinterpret_cast<MediaResourceIndex*>(aUserData);
-
-  nsresult rv = NS_OK;
-  uint32_t bytes = 0;
-
-  rv = resource->Read(static_cast<char *>(aBuffer), aLength, &bytes);
-
-  bool eof = !bytes;
-
-  return NS_FAILED(rv) ? -1 : eof ? 0 : 1;
-}
-
-static int webm_seek(int64_t aOffset, int aWhence, void *aUserData)
-{
-  MOZ_ASSERT(aUserData);
-  MediaResourceIndex* resource =
-    reinterpret_cast<MediaResourceIndex*>(aUserData);
-  nsresult rv = resource->Seek(aWhence, aOffset);
-  return NS_SUCCEEDED(rv) ? 0 : -1;
-}
-
-static int64_t webm_tell(void *aUserData)
-{
-  MOZ_ASSERT(aUserData);
-  MediaResourceIndex* resource =
-    reinterpret_cast<MediaResourceIndex*>(aUserData);
-  return resource->Tell();
-}
-
-static void webm_log(nestegg * context,
-                     unsigned int severity,
-                     char const * format, ...)
-{
-  if (!MOZ_LOG_TEST(gNesteggLog, LogLevel::Debug)) {
-    return;
-  }
-
-  va_list args;
-  char msg[256];
-  const char * sevStr;
-
-  switch(severity) {
-    case NESTEGG_LOG_DEBUG:
-      sevStr = "DBG";
-      break;
-    case NESTEGG_LOG_INFO:
-      sevStr = "INF";
-      break;
-    case NESTEGG_LOG_WARNING:
-      sevStr = "WRN";
-      break;
-    case NESTEGG_LOG_ERROR:
-      sevStr = "ERR";
-      break;
-    case NESTEGG_LOG_CRITICAL:
-      sevStr = "CRT";
-      break;
-    default:
-      sevStr = "UNK";
-      break;
-  }
-
-  va_start(args, format);
-
-  PR_snprintf(msg, sizeof(msg), "%p [Nestegg-%s] ", context, sevStr);
-  PR_vsnprintf(msg+strlen(msg), sizeof(msg)-strlen(msg), format, args);
-  MOZ_LOG(gNesteggLog, LogLevel::Debug, (msg));
-
-  va_end(args);
-}
-
-WebMReader::WebMReader(AbstractMediaDecoder* aDecoder)
-  : MediaDecoderReader(aDecoder)
-  , mContext(nullptr)
-  , mVideoTrack(0)
-  , mAudioTrack(0)
-  , mAudioStartUsec(-1)
-  , mAudioFrames(0)
-  , mSeekPreroll(0)
-  , mLastVideoFrameTime(0)
-  , mAudioCodec(-1)
-  , mVideoCodec(-1)
-  , mLayersBackendType(layers::LayersBackend::LAYERS_NONE)
-  , mHasVideo(false)
-  , mHasAudio(false)
-  , mResource(aDecoder->GetResource())
-{
-  MOZ_COUNT_CTOR(WebMReader);
-}
-
-WebMReader::~WebMReader()
-{
-  Cleanup();
-  mVideoPackets.Reset();
-  mAudioPackets.Reset();
-  MOZ_ASSERT(!mAudioDecoder);
-  MOZ_ASSERT(!mVideoDecoder);
-  MOZ_COUNT_DTOR(WebMReader);
-}
-
-RefPtr<ShutdownPromise>
-WebMReader::Shutdown()
-{
-  if (mAudioDecoder) {
-    mAudioDecoder->Shutdown();
-    mAudioDecoder = nullptr;
-  }
-
-  if (mVideoDecoder) {
-    mVideoDecoder->Shutdown();
-    mVideoDecoder = nullptr;
-  }
-
-  return MediaDecoderReader::Shutdown();
-}
-
-nsresult WebMReader::Init()
-{
-  mBufferedState = new WebMBufferedState;
-  return NS_OK;
-}
-
-void WebMReader::InitLayersBackendType()
-{
-  if (!IsVideoContentType(GetDecoder()->GetResource()->GetContentType())) {
-    // Not playing video, we don't care about the layers backend type.
-    return;
-  }
-  // Extract the layer manager backend type so that platform decoders
-  // can determine whether it's worthwhile using hardware accelerated
-  // video decoding.
-  MediaDecoderOwner* owner = mDecoder->GetOwner();
-  if (!owner) {
-    NS_WARNING("WebMReader without a decoder owner, can't get HWAccel");
-    return;
-  }
-
-  dom::HTMLMediaElement* element = owner->GetMediaElement();
-  NS_ENSURE_TRUE_VOID(element);
-
-  RefPtr<LayerManager> layerManager =
-    nsContentUtils::LayerManagerForDocument(element->OwnerDoc());
-  NS_ENSURE_TRUE_VOID(layerManager);
-
-  mLayersBackendType = layerManager->GetCompositorBackendType();
-}
-
-nsresult WebMReader::ResetDecode()
-{
-  mAudioFrames = 0;
-  mAudioStartUsec = -1;
-  nsresult res = NS_OK;
-  if (NS_FAILED(MediaDecoderReader::ResetDecode())) {
-    res = NS_ERROR_FAILURE;
-  }
-
-  if (mAudioDecoder) {
-    mAudioDecoder->ResetDecode();
-  }
-
-  mVideoPackets.Reset();
-  mAudioPackets.Reset();
-
-  return res;
-}
-
-void WebMReader::Cleanup()
-{
-  if (mContext) {
-    nestegg_destroy(mContext);
-    mContext = nullptr;
-  }
-}
-
-RefPtr<MediaDecoderReader::MetadataPromise>
-WebMReader::AsyncReadMetadata()
-{
-  RefPtr<MetadataHolder> metadata = new MetadataHolder();
-
-  if (NS_FAILED(RetrieveWebMMetadata(&metadata->mInfo)) ||
-      !metadata->mInfo.HasValidMedia()) {
-    return MetadataPromise::CreateAndReject(ReadMetadataFailureReason::METADATA_ERROR,
-                                            __func__);
-  }
-
-  return MetadataPromise::CreateAndResolve(metadata, __func__);
-}
-
-nsresult
-WebMReader::RetrieveWebMMetadata(MediaInfo* aInfo)
-{
-  MOZ_ASSERT(OnTaskQueue());
-
-  nestegg_io io;
-  io.read = webm_read;
-  io.seek = webm_seek;
-  io.tell = webm_tell;
-  io.userdata = &mResource;
-  int r = nestegg_init(&mContext, io, &webm_log, -1);
-  if (r == -1) {
-    return NS_ERROR_FAILURE;
-  }
-
-  uint64_t duration = 0;
-  r = nestegg_duration(mContext, &duration);
-  if (r == 0) {
-    mInfo.mMetadataDuration.emplace(TimeUnit::FromNanoseconds(duration));
-  }
-
-  unsigned int ntracks = 0;
-  r = nestegg_track_count(mContext, &ntracks);
-  if (r == -1) {
-    Cleanup();
-    return NS_ERROR_FAILURE;
-  }
-
-  for (uint32_t track = 0; track < ntracks; ++track) {
-    int id = nestegg_track_codec_id(mContext, track);
-    if (id == -1) {
-      Cleanup();
-      return NS_ERROR_FAILURE;
-    }
-    int type = nestegg_track_type(mContext, track);
-    if (!mHasVideo && type == NESTEGG_TRACK_VIDEO &&
-        mDecoder->GetImageContainer()) {
-      nestegg_video_params params;
-      r = nestegg_track_video_params(mContext, track, &params);
-      if (r == -1) {
-        Cleanup();
-        return NS_ERROR_FAILURE;
-      }
-
-      mVideoCodec = nestegg_track_codec_id(mContext, track);
-
-      if (!mVideoDecoder) {
-        mVideoDecoder = SoftwareWebMVideoDecoder::Create(this);
-      }
-
-      if (!mVideoDecoder ||
-          NS_FAILED(mVideoDecoder->Init(params.display_width,
-                                        params.display_height))) {
-        Cleanup();
-        return NS_ERROR_FAILURE;
-      }
-
-      // Picture region, taking into account cropping, before scaling
-      // to the display size.
-      unsigned int cropH = params.crop_right + params.crop_left;
-      unsigned int cropV = params.crop_bottom + params.crop_top;
-      nsIntRect pictureRect(params.crop_left,
-                            params.crop_top,
-                            params.width - cropH,
-                            params.height - cropV);
-
-      // If the cropping data appears invalid then use the frame data
-      if (pictureRect.width <= 0 ||
-          pictureRect.height <= 0 ||
-          pictureRect.x < 0 ||
-          pictureRect.y < 0) {
-        pictureRect.x = 0;
-        pictureRect.y = 0;
-        pictureRect.width = params.width;
-        pictureRect.height = params.height;
-      }
-
-      // Validate the container-reported frame and pictureRect sizes. This
-      // ensures that our video frame creation code doesn't overflow.
-      nsIntSize displaySize(params.display_width, params.display_height);
-      nsIntSize frameSize(params.width, params.height);
-      if (!IsValidVideoRegion(frameSize, pictureRect, displaySize)) {
-        // Video track's frame sizes will overflow. Ignore the video track.
-        continue;
-      }
-
-      mVideoTrack = track;
-      mHasVideo = true;
-
-      mInfo.mVideo.mDisplay = displaySize;
-      mPicture = pictureRect;
-      mInitialFrame = frameSize;
-
-      switch (params.stereo_mode) {
-      case NESTEGG_VIDEO_MONO:
-        mInfo.mVideo.mStereoMode = StereoMode::MONO;
-        break;
-      case NESTEGG_VIDEO_STEREO_LEFT_RIGHT:
-        mInfo.mVideo.mStereoMode = StereoMode::LEFT_RIGHT;
-        break;
-      case NESTEGG_VIDEO_STEREO_BOTTOM_TOP:
-        mInfo.mVideo.mStereoMode = StereoMode::BOTTOM_TOP;
-        break;
-      case NESTEGG_VIDEO_STEREO_TOP_BOTTOM:
-        mInfo.mVideo.mStereoMode = StereoMode::TOP_BOTTOM;
-        break;
-      case NESTEGG_VIDEO_STEREO_RIGHT_LEFT:
-        mInfo.mVideo.mStereoMode = StereoMode::RIGHT_LEFT;
-        break;
-      }
-    } else if (!mHasAudio && type == NESTEGG_TRACK_AUDIO) {
-      nestegg_audio_params params;
-      r = nestegg_track_audio_params(mContext, track, &params);
-      if (r == -1) {
-        Cleanup();
-        return NS_ERROR_FAILURE;
-      }
-
-      mAudioTrack = track;
-      mHasAudio = true;
-      mAudioCodec = nestegg_track_codec_id(mContext, track);
-      mCodecDelay = params.codec_delay / NS_PER_USEC;
-      mSeekPreroll = params.seek_preroll;
-
-      if (mAudioCodec == NESTEGG_CODEC_VORBIS) {
-        mAudioDecoder = new VorbisDecoder(this);
-      } else if (mAudioCodec == NESTEGG_CODEC_OPUS) {
-        mAudioDecoder = new OpusDecoder(this);
-      } else {
-        Cleanup();
-        return NS_ERROR_FAILURE;
-      }
-
-      if (!mAudioDecoder || NS_FAILED(mAudioDecoder->Init())) {
-        Cleanup();
-        return NS_ERROR_FAILURE;
-      }
-
-      unsigned int nheaders = 0;
-      r = nestegg_track_codec_data_count(mContext, track, &nheaders);
-      if (r == -1) {
-        Cleanup();
-        return NS_ERROR_FAILURE;
-      }
-
-      for (uint32_t header = 0; header < nheaders; ++header) {
-        unsigned char* data = 0;
-        size_t length = 0;
-        r = nestegg_track_codec_data(mContext, track, header, &data, &length);
-        if (r == -1) {
-          Cleanup();
-          return NS_ERROR_FAILURE;
-        }
-        if (NS_FAILED(mAudioDecoder->DecodeHeader(data, length))) {
-          Cleanup();
-          return NS_ERROR_FAILURE;
-        }
-      }
-      if (NS_FAILED(mAudioDecoder->FinishInit(mInfo.mAudio))) {
-        Cleanup();
-        return NS_ERROR_FAILURE;
-      }
-    }
-  }
-
-  mInfo.mMediaSeekable = nestegg_has_cues(mContext);
-
-  *aInfo = mInfo;
-
-  return NS_OK;
-}
-
-bool WebMReader::DecodeAudioPacket(NesteggPacketHolder* aHolder)
-{
-  MOZ_ASSERT(OnTaskQueue());
-
-  int r = 0;
-  unsigned int count = 0;
-  r = nestegg_packet_count(aHolder->Packet(), &count);
-  if (r == -1) {
-    return false;
-  }
-
-  int64_t tstamp = aHolder->Timestamp();
-  if (mAudioStartUsec == -1) {
-    // This is the first audio chunk. Assume the start time of our decode
-    // is the start of this chunk.
-    mAudioStartUsec = tstamp;
-  }
-  // If there's a gap between the start of this audio chunk and the end of
-  // the previous audio chunk, we need to increment the packet count so that
-  // the vorbis decode doesn't use data from before the gap to help decode
-  // from after the gap.
-  CheckedInt64 tstamp_frames = UsecsToFrames(tstamp, mInfo.mAudio.mRate);
-  CheckedInt64 decoded_frames = UsecsToFrames(mAudioStartUsec,
-                                              mInfo.mAudio.mRate);
-  if (!tstamp_frames.isValid() || !decoded_frames.isValid()) {
-    NS_WARNING("Int overflow converting WebM times to frames");
-    return false;
-  }
-  decoded_frames += mAudioFrames;
-  if (!decoded_frames.isValid()) {
-    NS_WARNING("Int overflow adding decoded_frames");
-    return false;
-  }
-  if (tstamp_frames.value() > decoded_frames.value()) {
-#ifdef DEBUG
-    int64_t gap_frames = tstamp_frames.value() - decoded_frames.value();
-    CheckedInt64 usecs = FramesToUsecs(gap_frames, mInfo.mAudio.mRate);
-    LOG(LogLevel::Debug, ("WebMReader detected gap of %lld, %lld frames, in audio",
-                       usecs.isValid() ? usecs.value() : -1,
-                       gap_frames));
-#endif
-    mAudioStartUsec = tstamp;
-    mAudioFrames = 0;
-  }
-
-  int32_t total_frames = 0;
-  for (uint32_t i = 0; i < count; ++i) {
-    unsigned char* data;
-    size_t length;
-    r = nestegg_packet_data(aHolder->Packet(), i, &data, &length);
-    if (r == -1) {
-      return false;
-    }
-    int64_t discardPadding = 0;
-    (void) nestegg_packet_discard_padding(aHolder->Packet(), &discardPadding);
-
-    if (!mAudioDecoder->Decode(data, length, aHolder->Offset(), tstamp, discardPadding, &total_frames)) {
-      mHitAudioDecodeError = true;
-      return false;
-    }
-  }
-
-  mAudioFrames += total_frames;
-
-  return true;
-}
-
-RefPtr<NesteggPacketHolder> WebMReader::NextPacket(TrackType aTrackType)
-{
-  // The packet queue that packets will be pushed on if they
-  // are not the type we are interested in.
-  WebMPacketQueue& otherPackets =
-    aTrackType == VIDEO ? mAudioPackets : mVideoPackets;
-
-  // The packet queue for the type that we are interested in.
-  WebMPacketQueue &packets =
-    aTrackType == VIDEO ? mVideoPackets : mAudioPackets;
-
-  // Flag to indicate that we do need to playback these types of
-  // packets.
-  bool hasType = aTrackType == VIDEO ? mHasVideo : mHasAudio;
-
-  // Flag to indicate that we do need to playback the other type
-  // of track.
-  bool hasOtherType = aTrackType == VIDEO ? mHasAudio : mHasVideo;
-
-  // Track we are interested in
-  uint32_t ourTrack = aTrackType == VIDEO ? mVideoTrack : mAudioTrack;
-
-  // Value of other track
-  uint32_t otherTrack = aTrackType == VIDEO ? mAudioTrack : mVideoTrack;
-
-  if (packets.GetSize() > 0) {
-    return packets.PopFront();
-  }
-
-  do {
-    RefPtr<NesteggPacketHolder> holder = DemuxPacket();
-    if (!holder) {
-      return nullptr;
-    }
-
-    if (hasOtherType && otherTrack == holder->Track()) {
-      // Save the packet for when we want these packets
-      otherPackets.Push(holder);
-      continue;
-    }
-
-    // The packet is for the track we want to play
-    if (hasType && ourTrack == holder->Track()) {
-      return holder;
-    }
-  } while (true);
-}
-
-RefPtr<NesteggPacketHolder>
-WebMReader::DemuxPacket()
-{
-  nestegg_packet* packet;
-  int r = nestegg_read_packet(mContext, &packet);
-  if (r <= 0) {
-    return nullptr;
-  }
-
-  unsigned int track = 0;
-  r = nestegg_packet_track(packet, &track);
-  if (r == -1) {
-    return nullptr;
-  }
-
-  // Figure out if this is a keyframe.
-  bool isKeyframe = false;
-  if (track == mAudioTrack) {
-    isKeyframe = true;
-  } else if (track == mVideoTrack) {
-    unsigned char* data;
-    size_t length;
-    r = nestegg_packet_data(packet, 0, &data, &length);
-    if (r == -1) {
-      return nullptr;
-    }
-    vpx_codec_stream_info_t si;
-    memset(&si, 0, sizeof(si));
-    si.sz = sizeof(si);
-    if (mVideoCodec == NESTEGG_CODEC_VP8) {
-      vpx_codec_peek_stream_info(vpx_codec_vp8_dx(), data, length, &si);
-    } else if (mVideoCodec == NESTEGG_CODEC_VP9) {
-      vpx_codec_peek_stream_info(vpx_codec_vp9_dx(), data, length, &si);
-    }
-    isKeyframe = si.is_kf;
-  }
-
-  int64_t offset = mResource.Tell();
-  RefPtr<NesteggPacketHolder> holder = new NesteggPacketHolder();
-  if (!holder->Init(packet, offset, track, isKeyframe)) {
-    return nullptr;
-  }
-
-  return holder;
-}
-
-bool WebMReader::DecodeAudioData()
-{
-  MOZ_ASSERT(OnTaskQueue());
-
-  RefPtr<NesteggPacketHolder> holder(NextPacket(AUDIO));
-  if (!holder) {
-    return false;
-  }
-
-  return DecodeAudioPacket(holder);
-}
-
-bool WebMReader::FilterPacketByTime(int64_t aEndTime, WebMPacketQueue& aOutput)
-{
-  // Push the video frames to the aOutput which's timestamp is less
-  // than aEndTime.
-  while (true) {
-    RefPtr<NesteggPacketHolder> holder(NextPacket(VIDEO));
-    if (!holder) {
-      break;
-    }
-    int64_t tstamp = holder->Timestamp();
-    if (tstamp >= aEndTime) {
-      PushVideoPacket(holder);
-      return true;
-    } else {
-      aOutput.PushFront(holder);
-    }
-  }
-
-  return false;
-}
-
-int64_t WebMReader::GetNextKeyframeTime(int64_t aTimeThreshold)
-{
-  WebMPacketQueue skipPacketQueue;
-  if (!FilterPacketByTime(aTimeThreshold, skipPacketQueue)) {
-    // Restore the packets before we return -1.
-    uint32_t size = skipPacketQueue.GetSize();
-    for (uint32_t i = 0; i < size; ++i) {
-      RefPtr<NesteggPacketHolder> packetHolder = skipPacketQueue.PopFront();
-      PushVideoPacket(packetHolder);
-    }
-    return -1;
-  }
-
-  // Find keyframe.
-  bool foundKeyframe = false;
-  int64_t keyframeTime = -1;
-  while (!foundKeyframe) {
-    RefPtr<NesteggPacketHolder> holder(NextPacket(VIDEO));
-    if (!holder) {
-      break;
-    }
-
-    if (holder->IsKeyframe()) {
-      foundKeyframe = true;
-      keyframeTime = holder->Timestamp();
-    }
-
-    skipPacketQueue.PushFront(holder);
-  }
-
-  uint32_t size = skipPacketQueue.GetSize();
-  for (uint32_t i = 0; i < size; ++i) {
-    RefPtr<NesteggPacketHolder> packetHolder = skipPacketQueue.PopFront();
-    PushVideoPacket(packetHolder);
-  }
-
-  return keyframeTime;
-}
-
-bool WebMReader::ShouldSkipVideoFrame(int64_t aTimeThreshold)
-{
-  return GetNextKeyframeTime(aTimeThreshold) != -1;
-}
-
-bool WebMReader::DecodeVideoFrame(bool &aKeyframeSkip, int64_t aTimeThreshold)
-{
-  if (!(aKeyframeSkip && ShouldSkipVideoFrame(aTimeThreshold))) {
-    LOG(LogLevel::Verbose, ("Reader [%p]: set the aKeyframeSkip to false.",this));
-    aKeyframeSkip = false;
-  }
-  return mVideoDecoder->DecodeVideoFrame(aKeyframeSkip, aTimeThreshold);
-}
-
-void WebMReader::PushVideoPacket(NesteggPacketHolder* aItem)
-{
-    mVideoPackets.PushFront(aItem);
-}
-
-RefPtr<MediaDecoderReader::SeekPromise>
-WebMReader::Seek(int64_t aTarget, int64_t aEndTime)
-{
-  nsresult res = SeekInternal(aTarget);
-  if (NS_FAILED(res)) {
-    return SeekPromise::CreateAndReject(res, __func__);
-  } else {
-    return SeekPromise::CreateAndResolve(aTarget, __func__);
-  }
-}
-
-nsresult WebMReader::SeekInternal(int64_t aTarget)
-{
-  MOZ_ASSERT(OnTaskQueue());
-  NS_ENSURE_TRUE(HaveStartTime(), NS_ERROR_FAILURE);
-  if (mVideoDecoder) {
-    nsresult rv = mVideoDecoder->Flush();
-    NS_ENSURE_SUCCESS(rv, rv);
-  }
-
-  LOG(LogLevel::Debug, ("Reader [%p] for Decoder [%p]: About to seek to %fs",
-                     this, mDecoder, double(aTarget) / USECS_PER_S));
-  if (NS_FAILED(ResetDecode())) {
-    return NS_ERROR_FAILURE;
-  }
-  uint32_t trackToSeek = mHasVideo ? mVideoTrack : mAudioTrack;
-  uint64_t target = aTarget * NS_PER_USEC;
-
-  if (mSeekPreroll) {
-    uint64_t startTime = uint64_t(StartTime()) * NS_PER_USEC;
-    if (target < mSeekPreroll || target - mSeekPreroll < startTime) {
-      target = startTime;
-    } else {
-      target -= mSeekPreroll;
-    }
-    LOG(LogLevel::Debug,
-        ("Reader [%p] SeekPreroll: %f StartTime: %f AdjustedTarget: %f",
-        this, double(mSeekPreroll) / NS_PER_S,
-        double(startTime) / NS_PER_S, double(target) / NS_PER_S));
-  }
-  int r = nestegg_track_seek(mContext, trackToSeek, target);
-  if (r != 0) {
-    LOG(LogLevel::Debug, ("Reader [%p]: track_seek for track %u failed, r=%d",
-                       this, trackToSeek, r));
-
-    // Try seeking directly based on cluster information in memory.
-    int64_t offset = 0;
-    bool rv = mBufferedState->GetOffsetForTime(target, &offset);
-    if (!rv) {
-      return NS_ERROR_FAILURE;
-    }
-
-    r = nestegg_offset_seek(mContext, offset);
-    LOG(LogLevel::Debug, ("Reader [%p]: attempted offset_seek to %lld r=%d",
-                       this, offset, r));
-    if (r != 0) {
-      return NS_ERROR_FAILURE;
-    }
-  }
-  return NS_OK;
-}
-
-media::TimeIntervals WebMReader::GetBuffered()
-{
-  MOZ_ASSERT(OnTaskQueue());
-  if (!HaveStartTime()) {
-    return media::TimeIntervals();
-  }
-  AutoPinned<MediaResource> resource(mDecoder->GetResource());
-
-  media::TimeIntervals buffered;
-  // Special case completely cached files.  This also handles local files.
-  if (mContext && resource->IsDataCachedToEndOfResource(0)) {
-    uint64_t duration = 0;
-    if (nestegg_duration(mContext, &duration) == 0) {
-      buffered +=
-        media::TimeInterval(media::TimeUnit::FromSeconds(0),
-                            media::TimeUnit::FromSeconds(duration / NS_PER_S));
-      return buffered;
-    }
-  }
-
-  // Either we the file is not fully cached, or we couldn't find a duration in
-  // the WebM bitstream.
-  MediaByteRangeSet ranges;
-  nsresult res = resource->GetCachedRanges(ranges);
-  NS_ENSURE_SUCCESS(res, media::TimeIntervals::Invalid());
-
-  for (uint32_t index = 0; index < ranges.Length(); index++) {
-    uint64_t start, end;
-    bool rv = mBufferedState->CalculateBufferedForRange(ranges[index].mStart,
-                                                        ranges[index].mEnd,
-                                                        &start, &end);
-    if (rv) {
-      int64_t startOffset = StartTime() * NS_PER_USEC;
-      NS_ASSERTION(startOffset >= 0 && uint64_t(startOffset) <= start,
-                   "startOffset negative or larger than start time");
-      if (!(startOffset >= 0 && uint64_t(startOffset) <= start)) {
-        startOffset = 0;
-      }
-      double startTime = (start - startOffset) / NS_PER_S;
-      double endTime = (end - startOffset) / NS_PER_S;
-      // If this range extends to the end of the file, the true end time
-      // is the file's duration.
-      if (mContext &&
-          resource->IsDataCachedToEndOfResource(ranges[index].mStart)) {
-        uint64_t duration = 0;
-        if (nestegg_duration(mContext, &duration) == 0) {
-          endTime = duration / NS_PER_S;
-        }
-      }
-      buffered += media::TimeInterval(media::TimeUnit::FromSeconds(startTime),
-                                      media::TimeUnit::FromSeconds(endTime));
-    }
-  }
-
-  return buffered;
-}
-
-void WebMReader::NotifyDataArrivedInternal()
-{
-  MOZ_ASSERT(OnTaskQueue());
-  AutoPinned<MediaResource> resource(mDecoder->GetResource());
-  MediaByteRangeSet byteRanges;
-  nsresult rv = resource->GetCachedRanges(byteRanges);
-
-  if (NS_FAILED(rv)) {
-    return;
-  }
-
-  for (auto& range : byteRanges) {
-    RefPtr<MediaByteBuffer> bytes =
-      resource->MediaReadAt(range.mStart, range.Length());
-    NS_ENSURE_TRUE_VOID(bytes);
-    mBufferedState->NotifyDataArrived(bytes->Elements(), bytes->Length(), range.mStart);
-  }
-}
-
-int WebMReader::GetVideoCodec()
-{
-  return mVideoCodec;
-}
-
-nsIntRect WebMReader::GetPicture()
-{
-  return mPicture;
-}
-
-nsIntSize WebMReader::GetInitialFrame()
-{
-  return mInitialFrame;
-}
-
-int64_t WebMReader::GetLastVideoFrameTime()
-{
-  return mLastVideoFrameTime;
-}
-
-void WebMReader::SetLastVideoFrameTime(int64_t aFrameTime)
-{
-  mLastVideoFrameTime = aFrameTime;
-}
-
-} // namespace mozilla
diff --git a/dom/media/webm/WebMReader.h b/dom/media/webm/WebMReader.h
deleted file mode 100644
index d974e1f7cb6..00000000000
--- a/dom/media/webm/WebMReader.h
+++ /dev/null
@@ -1,213 +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/. */
-#if !defined(WebMReader_h_)
-#define WebMReader_h_
-
-#include <stdint.h>
-
-#include "FlushableTaskQueue.h"
-#include "MediaDecoderReader.h"
-#include "MediaResource.h"
-#include "nsAutoRef.h"
-#include "nestegg/nestegg.h"
-
-#define VPX_DONT_DEFINE_STDINT_TYPES
-#include "vpx/vpx_codec.h"
-
-#include "mozilla/layers/LayersTypes.h"
-
-#include "NesteggPacketHolder.h"
-
-namespace mozilla {
-static const unsigned NS_PER_USEC = 1000;
-static const double NS_PER_S = 1e9;
-
-typedef TrackInfo::TrackType TrackType;
-
-class WebMBufferedState;
-class WebMPacketQueue;
-
-class WebMReader;
-
-// Class to handle various video decode paths
-class WebMVideoDecoder
-{
-public:
-  virtual nsresult Init(unsigned int aWidth = 0, unsigned int aHeight = 0) = 0;
-  virtual nsresult Flush() { return NS_OK; }
-  virtual void Shutdown() = 0;
-  virtual bool DecodeVideoFrame(bool &aKeyframeSkip,
-                                int64_t aTimeThreshold) = 0;
-  WebMVideoDecoder() {}
-  virtual ~WebMVideoDecoder() {}
-};
-
-// Class to handle various audio decode paths
-class WebMAudioDecoder
-{
-public:
-  virtual nsresult Init() = 0;
-  virtual void Shutdown() = 0;
-  virtual nsresult ResetDecode() = 0;
-  virtual nsresult DecodeHeader(const unsigned char* aData, size_t aLength) = 0;
-  virtual nsresult FinishInit(AudioInfo& aInfo) = 0;
-  virtual bool Decode(const unsigned char* aData, size_t aLength,
-                      int64_t aOffset, uint64_t aTstampUsecs,
-                      int64_t aDiscardPadding, int32_t* aTotalFrames) = 0;
-  virtual ~WebMAudioDecoder() {}
-};
-
-class WebMReader : public MediaDecoderReader
-{
-public:
-  explicit WebMReader(AbstractMediaDecoder* aDecoder);
-
-protected:
-  ~WebMReader();
-
-public:
-  // Returns a pointer to the decoder.
-  AbstractMediaDecoder* GetDecoder()
-  {
-    return mDecoder;
-  }
-
-  MediaInfo GetMediaInfo() { return mInfo; }
-
-  virtual RefPtr<ShutdownPromise> Shutdown() override;
-  virtual nsresult Init() override;
-  virtual nsresult ResetDecode() override;
-  virtual bool DecodeAudioData() override;
-
-  virtual bool DecodeVideoFrame(bool &aKeyframeSkip,
-                                int64_t aTimeThreshold) override;
-
-  virtual RefPtr<MetadataPromise> AsyncReadMetadata() override;
-
-  virtual RefPtr<SeekPromise>
-  Seek(int64_t aTime, int64_t aEndTime) override;
-
-  virtual media::TimeIntervals GetBuffered() override;
-
-  // Value passed to NextPacket to determine if we are reading a video or an
-  // audio packet.
-  enum TrackType {
-    VIDEO = 0,
-    AUDIO = 1
-  };
-
-  // Read a packet from the nestegg file. Returns nullptr if all packets for
-  // the particular track have been read. Pass VIDEO or AUDIO to indicate the
-  // type of the packet we want to read.
-  RefPtr<NesteggPacketHolder> NextPacket(TrackType aTrackType);
-
-  // Pushes a packet to the front of the video packet queue.
-  virtual void PushVideoPacket(NesteggPacketHolder* aItem);
-
-  int GetVideoCodec();
-  nsIntRect GetPicture();
-  nsIntSize GetInitialFrame();
-  int64_t GetLastVideoFrameTime();
-  void SetLastVideoFrameTime(int64_t aFrameTime);
-  layers::LayersBackend GetLayersBackendType() { return mLayersBackendType; }
-  uint64_t GetCodecDelay() { return mCodecDelay; }
-
-protected:
-  virtual void NotifyDataArrivedInternal() override;
-
-  // Decode a nestegg packet of audio data. Push the audio data on the
-  // audio queue. Returns true when there's more audio to decode,
-  // false if the audio is finished, end of file has been reached,
-  // or an un-recoverable read error has occured. The reader's monitor
-  // must be held during this call. The caller is responsible for freeing
-  // aPacket.
-  bool DecodeAudioPacket(NesteggPacketHolder* aHolder);
-
-  // Release context and set to null. Called when an error occurs during
-  // reading metadata or destruction of the reader itself.
-  void Cleanup();
-
-  virtual nsresult SeekInternal(int64_t aTime);
-
-  // Initializes mLayersBackendType if possible.
-  void InitLayersBackendType();
-
-  bool ShouldSkipVideoFrame(int64_t aTimeThreshold);
-
-private:
-  nsresult RetrieveWebMMetadata(MediaInfo* aInfo);
-
-  // Get the timestamp of keyframe greater than aTimeThreshold.
-  int64_t GetNextKeyframeTime(int64_t aTimeThreshold);
-  // Push the packets into aOutput which's timestamp is less than aEndTime.
-  // Return false if we reach the end of stream or something wrong.
-  bool FilterPacketByTime(int64_t aEndTime, WebMPacketQueue& aOutput);
-
-  // Internal method that demuxes the next packet from the stream. The caller
-  // is responsible for making sure it doesn't get lost.
-  RefPtr<NesteggPacketHolder> DemuxPacket();
-
-  // libnestegg context for webm container. Access on state machine thread
-  // or decoder thread only.
-  nestegg* mContext;
-
-  nsAutoPtr<WebMAudioDecoder> mAudioDecoder;
-  nsAutoPtr<WebMVideoDecoder> mVideoDecoder;
-
-  // Queue of video and audio packets that have been read but not decoded. These
-  // must only be accessed from the decode thread.
-  WebMPacketQueue mVideoPackets;
-  WebMPacketQueue mAudioPackets;
-
-  // Index of video and audio track to play
-  uint32_t mVideoTrack;
-  uint32_t mAudioTrack;
-
-  // Time in microseconds of the start of the first audio frame we've decoded.
-  int64_t mAudioStartUsec;
-
-  // Number of audio frames we've decoded since decoding began at mAudioStartMs.
-  uint64_t mAudioFrames;
-
-  // Number of microseconds that must be discarded from the start of the Stream.
-  uint64_t mCodecDelay;
-
-  // Nanoseconds to discard after seeking.
-  uint64_t mSeekPreroll;
-
-  // Calculate the frame duration from the last decodeable frame using the
-  // previous frame's timestamp.  In NS.
-  int64_t mLastVideoFrameTime;
-
-  // Parser state and computed offset-time mappings.  Shared by multiple
-  // readers when decoder has been cloned.  Main thread only.
-  RefPtr<WebMBufferedState> mBufferedState;
-
-  // Size of the frame initially present in the stream. The picture region
-  // is defined as a ratio relative to this.
-  nsIntSize mInitialFrame;
-
-  // Picture region, as relative to the initial frame size.
-  nsIntRect mPicture;
-
-  // Codec ID of audio track
-  int mAudioCodec;
-  // Codec ID of video track
-  int mVideoCodec;
-
-  layers::LayersBackend mLayersBackendType;
-
-  // Booleans to indicate if we have audio and/or video data
-  bool mHasVideo;
-  bool mHasAudio;
-
-  MediaResourceIndex mResource;
-
-};
-
-} // namespace mozilla
-
-#endif
diff --git a/dom/media/webm/moz.build b/dom/media/webm/moz.build
index 8dd3e99bf24..da11b0d99e5 100644
--- a/dom/media/webm/moz.build
+++ b/dom/media/webm/moz.build
@@ -6,20 +6,15 @@
 
 EXPORTS += [
     'NesteggPacketHolder.h',
-    'SoftwareWebMVideoDecoder.h',
     'WebMBufferedParser.h',
     'WebMDecoder.h',
     'WebMDemuxer.h',
-    'WebMReader.h',
 ]
 
 UNIFIED_SOURCES += [
-    'AudioDecoder.cpp',
-    'SoftwareWebMVideoDecoder.cpp',
     'WebMBufferedParser.cpp',
     'WebMDecoder.cpp',
     'WebMDemuxer.cpp',
-    'WebMReader.cpp',
 ]
 
 if CONFIG['MOZ_WEBM_ENCODER']:
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 8ac0ddb339c..394e7084be2 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -491,9 +491,6 @@ pref("media.mediasource.webm.enabled", true);
 #endif
 pref("media.mediasource.webm.audio.enabled", true);
 
-// Enable new MediaFormatReader architecture for plain webm.
-pref("media.format-reader.webm", true);
-
 #ifdef MOZ_WEBSPEECH
 pref("media.webspeech.recognition.enable", false);
 pref("media.webspeech.synth.enabled", false);