933042 - Add telemetry to WarnOnceAbout

Status: NEW

(Core :: DOM: Core & HTML, defect, P5)

Description

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

All the things that we warn about in WarnOnceAbout are things that we're trying to deprecate.

It would be great if we automatically reported telemetry data so that we can track usage for all things that trigger WarnOnceAbout warnings. That will make it much easier to judge when we can actually remove the implementation of whatever API we're trying to deprecate.

Comment 1

[(no longer active)]

It would be nice if we can steal code/ideas from chromium's UseCounter for this: <https://chromium.googlesource.com/chromium/blink/+/86b6367149de4019e2c8533412a3b1287c00a586/Source/core/page/UseCounter.h>.