--- a/dom/media/BufferMediaResource.h
+++ b/dom/media/BufferMediaResource.h
@@ -72,29 +72,16 @@ private:
   }
 
   nsresult GetCachedRanges(MediaByteRangeSet& aRanges) override
   {
     aRanges += MediaByteRange(0, int64_t(mLength));
     return NS_OK;
   }
 
-  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
-  {
-    // Not owned:
-    // - mBuffer
-    size_t size = MediaResource::SizeOfExcludingThis(aMallocSizeOf);
-    return size;
-  }
-
-  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
-  {
-    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
-  }
-
 private:
   const uint8_t * mBuffer;
   uint32_t mLength;
   uint32_t mOffset;
 };
 
 } // namespace mozilla
 

--- a/dom/media/MediaResource.h
+++ b/dom/media/MediaResource.h
@@ -211,24 +211,16 @@ public:
 
   /**
    * Fills aRanges with MediaByteRanges representing the data which is cached
    * in the media cache. Stream should be pinned during call and while
    * aRanges is being used.
    */
   virtual nsresult GetCachedRanges(MediaByteRangeSet& aRanges) = 0;
 
-  virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
-    return 0;
-  }
-
-  virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
-    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
-  }
-
 protected:
   virtual ~MediaResource() {};
 
 private:
   void Destroy();
   mozilla::ThreadSafeAutoRefCnt mRefCnt;
   NS_DECL_OWNINGTHREAD
 };
@@ -310,28 +302,27 @@ public:
     MediaResourceCallback* aCallback)
   {
     return nullptr;
   }
 
   // Returns true if the resource is a live stream.
   bool IsLiveStream() { return GetLength() == -1; }
 
-  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
+  virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
   {
     // Might be useful to track in the future:
     // - mChannel
     // - mURI (possibly owned, looks like just a ref from mChannel)
     // Not owned:
     // - mCallback
-    size_t size = MediaResource::SizeOfExcludingThis(aMallocSizeOf);
-    return size;
+    return 0;
   }
 
-  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
+  virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
   {
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
   }
 
 protected:
   BaseMediaResource(MediaResourceCallback* aCallback,
                     nsIChannel* aChannel,
                     nsIURI* aURI)

--- a/dom/media/hls/HLSResource.h
+++ b/dom/media/hls/HLSResource.h
@@ -78,23 +78,23 @@ public:
   }
 
   java::GeckoHLSResourceWrapper::GlobalRef GetResourceWrapper() {
     return mHLSResourceWrapper;
   }
 
   void Detach() { mDecoder = nullptr; }
 
-  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
   {
-    size_t size = MediaResource::SizeOfExcludingThis(aMallocSizeOf);
-    return size;
+    // TODO: track JAVA wrappers.
+    return 0;
   }
 
-  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
   {
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
   }
 
 private:
   friend class HLSResourceCallbacksSupport;
 
   void onDataAvailable();

--- a/dom/media/mediasource/MediaSourceResource.h
+++ b/dom/media/mediasource/MediaSourceResource.h
@@ -51,23 +51,23 @@ public:
 
   void SetEnded(bool aEnded)
   {
     MonitorAutoLock mon(mMonitor);
     mEnded = aEnded;
   }
 
 private:
-  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
   {
-    size_t size = MediaResource::SizeOfExcludingThis(aMallocSizeOf);
-    return size;
+    // TODO: track source buffers appended to MediaSource.
+    return 0;
   }
 
-  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
   {
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
   }
 
   Monitor mMonitor;
   bool mEnded; // protected by mMonitor
 };
 

--- a/dom/media/mediasource/SourceBufferResource.h
+++ b/dom/media/mediasource/SourceBufferResource.h
@@ -73,27 +73,23 @@ public:
     MOZ_ASSERT(OnTaskQueue());
     if (mInputBuffer.GetLength()) {
       aRanges += MediaByteRange(mInputBuffer.GetOffset(),
                                 mInputBuffer.GetLength());
     }
     return NS_OK;
   }
 
-  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
   {
     MOZ_ASSERT(OnTaskQueue());
-
-    size_t size = MediaResource::SizeOfExcludingThis(aMallocSizeOf);
-    size += mInputBuffer.SizeOfExcludingThis(aMallocSizeOf);
-
-    return size;
+    return mInputBuffer.SizeOfExcludingThis(aMallocSizeOf);
   }
 
-  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
   {
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
   }
 
   // Used by SourceBuffer.
   void AppendData(MediaByteBuffer* aData);
   void Ended();
   bool IsEnded()