--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -320,17 +320,16 @@ MediaDecoder::IsHeuristicDormantSupporte
 
 void
 MediaDecoder::UpdateDormantState(bool aDormantTimeout, bool aActivity)
 {
   MOZ_ASSERT(NS_IsMainThread());
 
   if (IsShutdown() ||
       !mDecoderStateMachine ||
-      mPlayState == PLAY_STATE_SHUTDOWN ||
       !mOwner->GetVideoFrameContainer() ||
       (mOwner->GetMediaElement() && mOwner->GetMediaElement()->IsBeingDestroyed()) ||
       !mDormantSupported)
   {
     return;
   }
 
   DECODER_LOG("UpdateDormantState aTimeout=%d aActivity=%d mIsDormant=%d "
@@ -420,22 +419,23 @@ MediaDecoder::CancelDormantTimer()
     mDormantTimer->Cancel();
   }
 }
 
 void
 MediaDecoder::Pause()
 {
   MOZ_ASSERT(NS_IsMainThread());
-  if (mPlayState == PLAY_STATE_LOADING ||
-      IsEnded()) {
+  if (IsShutdown()) {
+    return;
+  }
+  if (mPlayState == PLAY_STATE_LOADING || IsEnded()) {
     mNextState = PLAY_STATE_PAUSED;
     return;
   }
-
   ChangeState(PLAY_STATE_PAUSED);
 }
 
 void
 MediaDecoder::SetVolume(double aVolume)
 {
   MOZ_ASSERT(NS_IsMainThread());
   mVolume = aVolume;
@@ -499,17 +499,16 @@ MediaDecoder::MediaDecoder(MediaDecoderO
 #endif
   , mIgnoreProgressData(false)
   , mInfiniteStream(false)
   , mOwner(aOwner)
   , mFrameStats(new FrameStatistics())
   , mVideoFrameContainer(aOwner->GetVideoFrameContainer())
   , mPlaybackStatistics(new MediaChannelStatistics())
   , mPinnedForSeek(false)
-  , mShuttingDown(false)
   , mPausedForPlaybackRateNull(false)
   , mMinimizePreroll(false)
   , mMediaTracksConstructed(false)
   , mFiredMetadataLoaded(false)
   , mIsDormant(false)
   , mIsHeuristicDormantSupported(
       Preferences::GetBool("media.decoder.heuristic.dormant.enabled", false))
   , mHeuristicDormantTimeout(
@@ -606,18 +605,16 @@ void
 MediaDecoder::Shutdown()
 {
   MOZ_ASSERT(NS_IsMainThread());
 
   if (IsShutdown()) {
     return;
   }
 
-  mShuttingDown = true;
-
   // Unwatch all watch targets to prevent further notifications.
   mWatchManager.Shutdown();
 
   mResourceCallback->Disconnect();
 
 #ifdef MOZ_EME
   mCDMProxyPromiseHolder.RejectIfExists(true, __func__);
 #endif
@@ -1073,17 +1070,17 @@ MediaDecoder::IsSeeking() const
   MOZ_ASSERT(NS_IsMainThread());
   return mLogicallySeeking;
 }
 
 bool
 MediaDecoder::IsEndedOrShutdown() const
 {
   MOZ_ASSERT(NS_IsMainThread());
-  return IsEnded() || mPlayState == PLAY_STATE_SHUTDOWN;
+  return IsEnded() || IsShutdown();
 }
 
 bool
 MediaDecoder::OwnerHasError() const
 {
   MOZ_ASSERT(NS_IsMainThread());
   return IsShutdown() || mOwner->HasError();
 }
@@ -1122,17 +1119,17 @@ MediaDecoder::IsEnded() const
   MOZ_ASSERT(NS_IsMainThread());
   return mPlayState == PLAY_STATE_ENDED;
 }
 
 bool
 MediaDecoder::IsShutdown() const
 {
   MOZ_ASSERT(NS_IsMainThread());
-  return mShuttingDown;
+  return mPlayState == PLAY_STATE_SHUTDOWN;
 }
 
 void
 MediaDecoder::PlaybackEnded()
 {
   MOZ_ASSERT(NS_IsMainThread());
 
   if (IsShutdown() ||
@@ -1336,25 +1333,22 @@ MediaDecoder::SeekingStarted(MediaDecode
     mOwner->SeekStarted();
   }
 }
 
 void
 MediaDecoder::ChangeState(PlayState aState)
 {
   MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!IsShutdown(), "SHUTDOWN is the final state.");
 
   if (mNextState == aState) {
     mNextState = PLAY_STATE_PAUSED;
   }
 
-  if (mPlayState == PLAY_STATE_SHUTDOWN) {
-    return;
-  }
-
   DECODER_LOG("ChangeState %s => %s", PlayStateStr(), ToPlayStateStr(aState));
   mPlayState = aState;
 
   if (mPlayState == PLAY_STATE_PLAYING) {
     ConstructMediaTracks();
   } else if (IsEnded()) {
     RemoveMediaTracks();
   }

--- a/dom/media/MediaDecoder.h
+++ b/dom/media/MediaDecoder.h
@@ -679,22 +679,16 @@ protected:
   // this estimate is "decode time" (where the "current time" is the
   // time of the last decoded video frame).
   RefPtr<MediaChannelStatistics> mPlaybackStatistics;
 
   // True when our media stream has been pinned. We pin the stream
   // while seeking.
   bool mPinnedForSeek;
 
-  // True if the decoder is being shutdown. At this point all events that
-  // are currently queued need to return immediately to prevent javascript
-  // being run that operates on the element and decoder during shutdown.
-  // Read/Write from the main thread only.
-  bool mShuttingDown;
-
   // True if the playback is paused because the playback rate member is 0.0.
   bool mPausedForPlaybackRateNull;
 
   // Be assigned from media element during the initialization and pass to
   // AudioStream Class.
   dom::AudioChannel mAudioChannel;
 
   // True if the decoder has been directed to minimize its preroll before