Fix non-working sent-notification.

This is copy of the change reviewed (on internal repo) ag/3553436

Bug:71910324

Test: tested w/ KitchenSink. Sent a message to another phone and
received the sent-notification. Saw a notification pop-up on Mojave
when a new message is received.

Change-Id: I3bc25c95383530448e81f284fe6c609c7249a60b