Proposal: allow extensions to register web share targets

[carlosjeurissen]

Just like PWAs, it can be very beneficial for extensions to register web share targets. We can potentially just go for a 1:1 from the PWA implementation.

See:
https://web.dev/web-share-target/

[ianwill93]

I have an extension which can set local images and videos as wallpapers. It would be nice to share an edited video or photo from an app straight to the extension instead of navigating through windows and menus.

[ianwill93]

This could also be beneficial for fileBrowserHandler extensions which would otherwise have to be selected from the file explorer on Chrome OS.

[dotproto]

Chromium issue: crbug.com/1363239