Validate ringtone URIs before setting am: 7ba175eaeb am: 236f1a0f17 am: 623d966fac am: a4a9b9f0e7

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Settings/+/24956689

Change-Id: I2ed08af5bb3839d2a19403a6c65fd6c2c6ccce9e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>