1691156 - Enable recording telemetry events via C++ RecordEvent calls in child processes

Status: NEW

(Toolkit :: Telemetry, enhancement, P3)

Description

[Jon Bauman [:jbauman:]]

When calling Telemetry::SetEventRecordingEnabled followed by Telemetry::RecordEvent in a content process, the event data is successfully transmitted via IPC to the parent process and the TelemetryEvent::RecordChildEvents function, but subsequently fails the check on gEnabledCategories in RecordEvent because unlike the RecordEvent call in the child process, there's no IPC machinery to convey the result of the SetEventRecordingEnabled call from the child to parent process. As a result, the telemetry events are not actually recorded.

It may be possible in some circumstances to work around this limitation when Telemetry::SetEventRecordingEnabled can be called at an appropriate place in the parent process, but in general this behavior is unexpected and seems to just be a bit of API implementation that was overlooked.