gather
Collect and return telemetry about send-tab attempts.
Applications that register the DeviceCapability::SendTab capability should also arrange to submit "sync ping" telemetry. Calling this method will return a JSON string of telemetry data that can be incorporated into that ping.
Sorry, this is not particularly carefully documented because it is intended as a stop-gap until we get native Glean support. If you know how to submit a sync ping, you'll know what to do with the contents of the JSON string.