1991617 - Implement MediaStreamTrackProcessor behind a pref

Status: NEW

(Core :: WebRTC: Audio/Video, task, P3)

Comment 1

[Andreas Pehrson [:pehrsons]]

Attachment: Bug 1991617 - Add WPT for keeping cross-origin media out of MediaStreamTrackProcessor in a worker. r?#webrtc-reviewers

A worker has no consumer that can render a MediaStreamTrack without
exposing its data to script, so data under a principal the worker cannot
access must never reach it. Per mediacapture-fromelement's security
considerations this includes media that switches to a cross-origin source
while captured. The test captures a same-origin, a cross-origin and a
CORS-loaded video with mozCaptureStream(), transfers the track to a worker
and reads frames with MediaStreamTrackProcessor, expecting real frames only
for the same-origin and CORS cases.

MediaStreamTrackProcessor is not implemented, so the expectations are FAIL
until it is. Implementing it, or any other worker consumer of track data,
must flip them.