Resolve cross account user ringtone validation.

Resolves a vulnerability found with the lack of cross account user ringtone
validation in RingtoneFactory. The reporter found that a ringtone file owned by a different user can be accessed and played by the user who does not own that file.

Bug: 356604577
Flag: EXEMPT Critical CVE bugfix
Test: RingtoneFactoryTest
Change-Id: Ie28e8d0890086caada561ed27dd660836e6aa6bb
3 files changed