Conpherence - fix missing method

Summary: Fixes T7669. Broken by D12163 re-factoring and foolihardiness of test coverage. Notably / interestingly, this was broken before D12163 from not implementing policy correctly, so Conpherence has been broken for a bit with few reports.

Test Plan: had user send himself a message

Reviewers: chad, epriestley

Reviewed By: chad, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7669

Differential Revision: https://secure.phabricator.com/D12177