Bug 1045186 - [B2G][Ringtones] The user can not share ringtone through MMS

If filename can be null for custom ringtones, maybe do filename || name in the filenames array?  IIRC, the filenames array is there because of a long ago bug where memory-backed blob issues were preventing the bluetooth sending code from working correctly and it had to be modified to read files directly.  In practice, the filenames probably don't matter, but some apps might display them, I suppose so something more-or-less human readable (instead of "null" or "undefined") would be ideal.