Bug 1001383 - HTMLMediaElement::UpdateAudioChannelPlayingState() should use system principal because calling AudioChannel API, r=bz

content/html/content/src/HTMLMediaElement.cpp

@@ -3848,6 +3848,11 @@ void HTMLMediaElement::UpdateAudioChannelPlayingState()
       mAudioChannelAgent->SetVisibilityState(!OwnerDoc()->Hidden());
     }
 
+    // This is needed to pass nsContentUtils::IsCallerChrome().
+    // AudioChannel API should not called from content but it can happen that
+    // this method has some content JS in its stack.
+    AutoNoJSAPI nojsapi;
+
     if (mPlayingThroughTheAudioChannel) {
       int32_t canPlay;
       mAudioChannelAgent->StartPlaying(&canPlay);