--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -520,17 +520,16 @@ MediaDecoder::MediaDecoder(MediaDecoderO
   , INIT_MIRROR(mStateMachineIsShutdown, true)
   , INIT_MIRROR(mBuffered, TimeIntervals())
   , INIT_MIRROR(mNextFrameStatus, MediaDecoderOwner::NEXT_FRAME_UNINITIALIZED)
   , INIT_MIRROR(mCurrentPosition, 0)
   , INIT_MIRROR(mStateMachineDuration, NullableTimeUnit())
   , INIT_MIRROR(mPlaybackPosition, 0)
   , INIT_MIRROR(mIsAudioDataAudible, false)
   , INIT_CANONICAL(mVolume, 0.0)
-  , INIT_CANONICAL(mPlaybackRate, 1.0)
   , INIT_CANONICAL(mPreservesPitch, true)
   , INIT_CANONICAL(mEstimatedDuration, NullableTimeUnit())
   , INIT_CANONICAL(mExplicitDuration, Maybe<double>())
   , INIT_CANONICAL(mPlayState, PLAY_STATE_LOADING)
   , INIT_CANONICAL(mNextState, PLAY_STATE_PAUSED)
   , INIT_CANONICAL(mLogicallySeeking, false)
   , INIT_CANONICAL(mSameOriginMedia, false)
   , INIT_CANONICAL(mMediaPrincipalHandle, PRINCIPAL_HANDLE_NONE)

--- a/dom/media/MediaDecoder.h
+++ b/dom/media/MediaDecoder.h
@@ -759,17 +759,17 @@ protected:
 
   // Used to distinguish whether the audio is producing sound.
   Mirror<bool> mIsAudioDataAudible;
 
   // Volume of playback.  0.0 = muted. 1.0 = full volume.
   Canonical<double> mVolume;
 
   // PlaybackRate and pitch preservation status we should start at.
-  Canonical<double> mPlaybackRate;
+  double mPlaybackRate = 1;
 
   Canonical<bool> mPreservesPitch;
 
   // Media duration according to the demuxer's current estimate.
   // Note that it's quite bizarre for this to live on the main thread - it would
   // make much more sense for this to be owned by the demuxer's task queue. But
   // currently this is only every changed in NotifyDataArrived, which runs on
   // the main thread. That will need to be cleaned up at some point.
@@ -822,19 +822,16 @@ protected:
   // True if the decoder is visible.
   Canonical<bool> mIsVisible;
 
 public:
   AbstractCanonical<media::NullableTimeUnit>* CanonicalDurationOrNull() override;
   AbstractCanonical<double>* CanonicalVolume() {
     return &mVolume;
   }
-  AbstractCanonical<double>* CanonicalPlaybackRate() {
-    return &mPlaybackRate;
-  }
   AbstractCanonical<bool>* CanonicalPreservesPitch() {
     return &mPreservesPitch;
   }
   AbstractCanonical<media::NullableTimeUnit>* CanonicalEstimatedDuration() {
     return &mEstimatedDuration;
   }
   AbstractCanonical<Maybe<double>>* CanonicalExplicitDuration() {
     return &mExplicitDuration;

--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -740,17 +740,16 @@ MediaDecoderStateMachine::MediaDecoderSt
   mAudioOffloading(false),
   INIT_MIRROR(mBuffered, TimeIntervals()),
   INIT_MIRROR(mIsReaderSuspended, true),
   INIT_MIRROR(mEstimatedDuration, NullableTimeUnit()),
   INIT_MIRROR(mExplicitDuration, Maybe<double>()),
   INIT_MIRROR(mPlayState, MediaDecoder::PLAY_STATE_LOADING),
   INIT_MIRROR(mNextPlayState, MediaDecoder::PLAY_STATE_PAUSED),
   INIT_MIRROR(mVolume, 1.0),
-  INIT_MIRROR(mLogicalPlaybackRate, 1.0),
   INIT_MIRROR(mPreservesPitch, true),
   INIT_MIRROR(mSameOriginMedia, false),
   INIT_MIRROR(mMediaPrincipalHandle, PRINCIPAL_HANDLE_NONE),
   INIT_MIRROR(mPlaybackBytesPerSecond, 0.0),
   INIT_MIRROR(mPlaybackRateReliable, true),
   INIT_MIRROR(mDecoderPosition, 0),
   INIT_MIRROR(mMediaSeekable, true),
   INIT_MIRROR(mMediaSeekableOnlyInBufferedRanges, false),
@@ -802,17 +801,16 @@ MediaDecoderStateMachine::Initialization
   // Connect mirrors.
   mBuffered.Connect(mReader->CanonicalBuffered());
   mIsReaderSuspended.Connect(mReader->CanonicalIsSuspended());
   mEstimatedDuration.Connect(aDecoder->CanonicalEstimatedDuration());
   mExplicitDuration.Connect(aDecoder->CanonicalExplicitDuration());
   mPlayState.Connect(aDecoder->CanonicalPlayState());
   mNextPlayState.Connect(aDecoder->CanonicalNextPlayState());
   mVolume.Connect(aDecoder->CanonicalVolume());
-  mLogicalPlaybackRate.Connect(aDecoder->CanonicalPlaybackRate());
   mPreservesPitch.Connect(aDecoder->CanonicalPreservesPitch());
   mSameOriginMedia.Connect(aDecoder->CanonicalSameOriginMedia());
   mMediaPrincipalHandle.Connect(aDecoder->CanonicalMediaPrincipalHandle());
   mPlaybackBytesPerSecond.Connect(aDecoder->CanonicalPlaybackBytesPerSecond());
   mPlaybackRateReliable.Connect(aDecoder->CanonicalPlaybackRateReliable());
   mDecoderPosition.Connect(aDecoder->CanonicalDecoderPosition());
   mMediaSeekable.Connect(aDecoder->CanonicalMediaSeekable());
   mMediaSeekableOnlyInBufferedRanges.Connect(aDecoder->CanonicalMediaSeekableOnlyInBufferedRanges());
@@ -1703,17 +1701,16 @@ MediaDecoderStateMachine::Shutdown()
   // Disconnect canonicals and mirrors before shutting down our task queue.
   mBuffered.DisconnectIfConnected();
   mIsReaderSuspended.DisconnectIfConnected();
   mEstimatedDuration.DisconnectIfConnected();
   mExplicitDuration.DisconnectIfConnected();
   mPlayState.DisconnectIfConnected();
   mNextPlayState.DisconnectIfConnected();
   mVolume.DisconnectIfConnected();
-  mLogicalPlaybackRate.DisconnectIfConnected();
   mPreservesPitch.DisconnectIfConnected();
   mSameOriginMedia.DisconnectIfConnected();
   mMediaPrincipalHandle.DisconnectIfConnected();
   mPlaybackBytesPerSecond.DisconnectIfConnected();
   mPlaybackRateReliable.DisconnectIfConnected();
   mDecoderPosition.DisconnectIfConnected();
   mMediaSeekable.DisconnectIfConnected();
   mMediaSeekableOnlyInBufferedRanges.DisconnectIfConnected();

--- a/dom/media/MediaDecoderStateMachine.h
+++ b/dom/media/MediaDecoderStateMachine.h
@@ -889,21 +889,16 @@ private:
 
   // The current play state and next play state, mirrored from the main thread.
   Mirror<MediaDecoder::PlayState> mPlayState;
   Mirror<MediaDecoder::PlayState> mNextPlayState;
 
   // Volume of playback. 0.0 = muted. 1.0 = full volume.
   Mirror<double> mVolume;
 
-  // TODO: The separation between mPlaybackRate and mLogicalPlaybackRate is a
-  // kludge to preserve existing fragile logic while converting this setup to
-  // state-mirroring. Some hero should clean this up.
-  Mirror<double> mLogicalPlaybackRate;
-
   // Pitch preservation for the playback rate.
   Mirror<bool> mPreservesPitch;
 
   // True if the media is same-origin with the element. Data can only be
   // passed to MediaStreams when this is true.
   Mirror<bool> mSameOriginMedia;
 
   // An identifier for the principal of the media. Used to track when