Revert "Revert "Ringer mode button state a11y""

This reverts commit 1795e889e9a0ca724b7fcbefdc5b4b13148aeb10.

Reason for revert: Adding in a fix (null-pointer check)

Change-Id: Ic8145c3a6420ffdcfbdd197115b37151d4a77efc
2 files changed