Bug 1301675 - Clarify why we don't need to do anything on DecoderCaptureTrackSource::Stop(). r=jib

MozReview-Commit-ID: H1zaO1FKWvK

dom/html/HTMLMediaElement.cpp

@@ -2363,9 +2363,10 @@ public:
 
   void Stop() override
   {
-    // XXX Fix in later patch.
-    NS_ERROR("We're reporting remote=true to not be stoppable. "
-             "Stop() should not be called.");
+    // We don't notify the source that a track was stopped since it will keep
+    // producing tracks until the element ends. The decoder also needs the
+    // tracks it created to be live at the source since the decoder's clock is
+    // based on MediaStreams during capture.
   }
 
   void NotifyDecoderPrincipalChanged() override