--- a/dom/media/MediaFormatReader.cpp
+++ b/dom/media/MediaFormatReader.cpp
@@ -465,59 +465,60 @@ public:
           data->mVideoDemuxer = nullptr;
         }
         data->mDemuxer = nullptr;
       }));
   }
 
   RefPtr<MediaDataDemuxer::InitPromise> Init();
 
-  already_AddRefed<MediaTrackDemuxer> GetTrackDemuxer(TrackType aTrack, uint32_t aTrackNumber)
+  already_AddRefed<MediaTrackDemuxer>
+  GetTrackDemuxer(TrackType aTrack, uint32_t aTrackNumber) const
   {
     MOZ_RELEASE_ASSERT(mData && mData->mInitDone);
 
     switch (aTrack) {
       case TrackInfo::kAudioTrack:
         return mData->mAudioDemuxer.forget();
       case TrackInfo::kVideoTrack:
         return mData->mVideoDemuxer.forget();
       default:
         return nullptr;
     }
   }
 
-  uint32_t GetNumberTracks(TrackType aTrack)
+  uint32_t GetNumberTracks(TrackType aTrack) const
   {
     MOZ_RELEASE_ASSERT(mData && mData->mInitDone);
 
     switch (aTrack) {
       case TrackInfo::kAudioTrack:
         return mData->mNumAudioTrack;
       case TrackInfo::kVideoTrack:
         return mData->mNumVideoTrack;
       default:
         return 0;
     }
   }
 
-  bool IsSeekable()
+  bool IsSeekable() const
   {
     MOZ_RELEASE_ASSERT(mData && mData->mInitDone);
 
     return mData->mSeekable;
   }
 
-  bool IsSeekableOnlyInBufferedRanges()
+  bool IsSeekableOnlyInBufferedRanges() const
   {
     MOZ_RELEASE_ASSERT(mData && mData->mInitDone);
 
     return mData->mSeekableOnlyInBufferedRange;
   }
 
-  UniquePtr<EncryptionInfo> GetCrypto()
+  UniquePtr<EncryptionInfo> GetCrypto() const
   {
     MOZ_RELEASE_ASSERT(mData && mData->mInitDone);
 
     if (!mData->mCrypto) {
       return nullptr;
     }
     auto crypto = MakeUnique<EncryptionInfo>();
     *crypto = *mData->mCrypto;