Don't show media controls when there is a persistent video.

content/public/common/web_preferences.h

Index: content/public/common/web_preferences.h
diff --git a/content/public/common/web_preferences.h b/content/public/common/web_preferences.h
index b5f363f048ad31ee6d1b69ee91cfe4651fbb6dd1..c7476907b33fdcfc79725afbcf0f0f208deaa961 100644
--- a/content/public/common/web_preferences.h
+++ b/content/public/common/web_preferences.h
@@ -283,6 +283,9 @@ struct CONTENT_EXPORT WebPreferences {
   // Whether it is a presentation receiver.
   bool presentation_receiver;
 
+  // If disabled, media controls should never be used.
+  bool media_controls_enabled;
+
   // We try to keep the default values the same as the default values in
   // chrome, except for the cases where it would require lots of extra work for
   // the embedder to use the same default value.