ensure RequestStorageId cannot be accessed remotely
In https://bugzilla.mozilla.org/show_bug.cgi?id=1420836 (for Firefox 59), Mozilla added a GMP API that appears to return a machine identifier (maybe based on MAC address). Is there any chance this could be accessed by a remote site and used as a unique fingerprint? Or do we disable enough of EME/GMP code that this is not a concern?