A permission request for using an EME Content Decryption Module.
WebKitMediaKeySystemPermissionRequest represents a request for permission to decide whether WebKit should use the given CDM to access
protected media when requested through the MediaKeySystem API.
When a WebKitMediaKeySystemPermissionRequest is not handled by the user, it is denied by default.
When handling this permission request the application may perform additional installation of the requested CDM, unless it is already
present on the host system.