This function is used for some old telemetry probes, and it is tied to a media element. This means that in order to call that function, what we do right now is to get a reference to the hidden window, use it to create a <video> element and then call the function, which is a bit wasteful.

I saw it as I'm on a quest to reduce the usage of the hidden window. As a workaround I can just use one existing window (since the element doesn't need to be appended, just created), but it would be nicer if this was a static function somewhere else as it doesn't really the media element for anything.

However, I pinged cpearce on IRC about moving that function and he suggested that I asked around to see if these probes are still used, or if they (and this function) can be entirely removed. Apparently that data was more useful when we still supported XP/Vista.

Nils, what do you say? Is this information still being used or can it be removed?

I noticed that the related telemetry probes are set to expire on version 68

From a quick look I would say we can probably remove this code. Jean-Yves do you have any thoughts if this is still delivering useful information or not?

Jean-Yves, any thoughts here?

This probe just expired, so if it's still useful it needs to be bumped in TelemetryHistograms.json, or otherwise we can use this bug to remove it.

https://telemetry.mozilla.org/probe-dictionary/?search=VIDEO_CAN_&channel=nightly&constraint=is_expired&version=68

Let's update the telemetry code, this code will be useful for properly implementing media capabilities.