Backed out changeset 443a94083e00 (bug 1294605)

dom/html/HTMLMediaElement.cpp

@@ -2210,11 +2210,15 @@ public:
                              nsString())
     , mCapturedTrackSource(aCapturedTrackSource)
   {
+    mCapturedTrackSource->RegisterSink(this);
   }
 
   void Destroy() override
   {
     MOZ_ASSERT(mCapturedTrackSource);
+    if (mCapturedTrackSource) {
+      mCapturedTrackSource->UnregisterSink(this);
+    }
   }
 
   MediaSourceEnum GetMediaSource() const override