Intent to ship: Document Picture-in-Picture API

[Vincent Hilla]

As of Firefox 151, I intend to enable the Document Picture-in-Picture API by default. It was developed behind the dom.documentpip.enabled preference. The status in other browsers is: shipped in Blink, not implemented in WebKit.

Bug to turn on by default: https://bugzilla.mozilla.org/show_bug.cgi?id=2006594

Standard: https://wicg.github.io/document-picture-in-picture/

Work to upstream is ongoing, and it is expected to move to either HTML or to a standards-track venue (see https://github.com/WICG/document-picture-in-picture/issues/147). The feature has already shipped in Blink and is seeing real-world usage (e.g. Spotify, Bug 1985536; TikTok, Bug 1903555).

The feature was previously discussed in this "Intent to Prototype" thread: https://groups.google.com/a/mozilla.org/g/dev-platform/c/VgoQBO-YUW4/m/Y-ycAoOmAAAJ