1662096 - privacy.firstparty.isolate prevents YTMNDs from playing

Status: NEW

(Core :: DOM: Core & HTML, defect, P3)

Description

[NewKidOnTheBlock]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:80.0) Gecko/20100101 Firefox/80.0

Steps to reproduce:

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:80.0) Gecko/20100101 Firefox/80.0

Steps to reproduce:
Go to about:config
Set privacy.firstparty.isolate to true
Go to https://regisiv.ytmnd.com/
Media does not play!

If privacy.firstparty.isolate is set to false, all YTMNDs play just fine.

Actual results:

No precaching is shown.
YTMNDs can not be played.

Expected results:

YTMNDs should precache and play while having privacy.firstparty.isolate set to true.

Comment 1

[Release mgmt bot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 2

[Release mgmt bot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 3

[Simon Mainey]

FPI = false

timestamp    Logo SVG load() common.js:742:17
timestamp    Logo SVG title animation ended. Starting data fetch.. common.js:742:17
timestamp    Site data loaded. common.js:742:17
timestamp    Testing audio codec for ogg[audio/ogg; codecs="opus"]:  probably common.js:742:17
timestamp    Testing audio codec for mp3[audio/mpeg]:  maybe
... etc

FPI = true

timestamp    Logo SVG load() common.js:742:17
Uncaught TypeError: document.getElementById(...).contentDocument is null ytmnd_loader.js:846:18
... and that's it

SVG animation fails

Comment 4

[Kestrel]

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=3c5385bd993b8e194fb0a73f54159892077d9d49&tochange=94dcb2fb29ce891e55f198246edc299d8a72a333

Regressed by Bug 1646899.