Google Favicon Allow-listing

Google is often used as a favicon cache for websites and tools. It probably could use an allow-listing.

Example:
https://www.google.com/s2/favicons?domain=www.virustotal.com&sz=64
https://www.virustotal.com/

Google provides a favicon-fetching (cached usually) API, allowing size (sz) and domain (url) (possibly others but at least these two should be allowed, possible trim domain). The API is called Shared Stuff (s2).

I'm using *.google.*/^/s2/favicons$ with allow-list domain and sz.

Start by locating the URL allow-listing rules that handle Google paths and compare them with the example /s2/favicons request. Confirm that the domain and sz parameters are permitted, that the domain can be trimmed if supported, and that the supplied favicon URL remains cleanly handled.

Written by the indexing model from the issue text.