Compression dictionary support - now live in Chrome 130

Thank you all for your help in refining the compression dictionary spec.
Chrome 130 released to stable with support for the latest draft (ungated -
no longer an experiment).

Both Brotli and ZStandard encodings are included. The current release
enables dictionary support only for secure contexts where the certificate
is rooted in a well-known trust root (i.e. disabled for  MITM
intercepts/proxies). Once there are enough impactful sites using it that we
expect IT teams will notice the breakage even if they don't test for it
directly we will remove the trust root restriction. There will still be a
short-term enterprise policy to allow for disabling it until vendors fix
their implementations but the goal is to force that to happen.

If you're interested in trying it out or have any questions, don't hesitate
to ping me.


On a related note, if you are interested in helping review the shared
brotli stream format draft (which is a blocker for the compression
dictionary draft to be published), if you could send a review to Francesca
this week it would very much be appreciated. This one is an informational
draft that documents the stream format used by brotli with an external
dictionary and the main concern is to make sure the draft contains
everything someone would need to create or consume shared brotli streams.

https://datatracker.ietf.org/doc/draft-vandevenne-shared-brotli-format/

Thanks,

-Pat