--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -392,17 +392,16 @@ MediaDecoder::MediaDecoder(MediaDecoderO
   , 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)
   , INIT_CANONICAL(mPlaybackBytesPerSecond, 0.0)
   , INIT_CANONICAL(mPlaybackRateReliable, true)
   , INIT_CANONICAL(mDecoderPosition, 0)
-  , INIT_CANONICAL(mMediaSeekable, true)
   , INIT_CANONICAL(mMediaSeekableOnlyInBufferedRanges, false)
   , INIT_CANONICAL(mIsVisible, !aOwner->IsHidden())
   , mTelemetryReported(false)
 {
   MOZ_COUNT_CTOR(MediaDecoder);
   MOZ_ASSERT(NS_IsMainThread());
   MediaMemoryTracker::AddMediaDecoder(this);
 

--- a/dom/media/MediaDecoder.h
+++ b/dom/media/MediaDecoder.h
@@ -661,16 +661,19 @@ protected:
 
   // True if audio tracks and video tracks are constructed and added into the
   // track list, false if all tracks are removed from the track list.
   bool mMediaTracksConstructed;
 
   // True if we've already fired metadataloaded.
   bool mFiredMetadataLoaded;
 
+  // True if the media is seekable (i.e. supports random access).
+  bool mMediaSeekable = true;
+
   // Stores media info, including info of audio tracks and video tracks, should
   // only be accessed from main thread.
   nsAutoPtr<MediaInfo> mInfo;
 
   // Tracks the visiblity status from HTMLMediaElement
   bool mElementVisible;
 
   // If true, forces the decoder to be considered hidden.
@@ -760,19 +763,16 @@ protected:
   Canonical<bool> mPlaybackRateReliable;
 
   // Current decoding position in the stream. This is where the decoder
   // is up to consuming the stream. This is not adjusted during decoder
   // seek operations, but it's updated at the end when we start playing
   // back again.
   Canonical<int64_t> mDecoderPosition;
 
-  // True if the media is seekable (i.e. supports random access).
-  Canonical<bool> mMediaSeekable;
-
   // True if the media is only seekable within its buffered ranges.
   Canonical<bool> mMediaSeekableOnlyInBufferedRanges;
 
   // True if the decoder is visible.
   Canonical<bool> mIsVisible;
 
 public:
   AbstractCanonical<media::NullableTimeUnit>* CanonicalDurationOrNull() override;
@@ -807,19 +807,16 @@ public:
     return &mPlaybackBytesPerSecond;
   }
   AbstractCanonical<bool>* CanonicalPlaybackRateReliable() {
     return &mPlaybackRateReliable;
   }
   AbstractCanonical<int64_t>* CanonicalDecoderPosition() {
     return &mDecoderPosition;
   }
-  AbstractCanonical<bool>* CanonicalMediaSeekable() {
-    return &mMediaSeekable;
-  }
   AbstractCanonical<bool>* CanonicalMediaSeekableOnlyInBufferedRanges() {
     return &mMediaSeekableOnlyInBufferedRanges;
   }
   AbstractCanonical<bool>* CanonicalIsVisible() {
     return &mIsVisible;
   }
 
 private: