registerProtoclHandler() is a method that “allows Web sites to register themselves as possible handlers for particular schemes” (from whatwg/html). The set of schemes that can be associated with custom handlers is restricted to a safelist and schemes that begin with web+ (whatwg/html#safelisted-schemes).

The current list of Google Chrome’s whitelisted schemes (as of August 27, 2018) are: bitcoin, geo, im, irc, ircs, magnet, mailto, mms, news, nntp, openpgp4fpr, sip, sms, smsto, ssh, tel, urn, webcal, wtai, and xmpp.

We are proposing the extension of the safe list with the following schemes:

* dat, dweb, ipfs, ipns, ssb.

These are schemes that are used with distributed web protocols. Allowing custom handlers for these schemes aid experimentation of these protocols on Chrome.

* bzr, bzr+ftp, bzr+lp, bzr+http, bzr+https, bzr+sftp, bzr+ssh, cvs, cvs+ext, cvs+pserver, cvs+ssh, darcs+http, darcs+https, darcs+ssh, git, git+http, git+https, git+ssh, hg, hg+http, hg+https, hg+ssh, hg+static-http, lp, svn, svn+http, svn+https, svn+ssh.

These schemes correspond to source control protocols along with variants for specifying subprotocols or underlying transports.

* map, gmap, bingmap, location

Planned use in provider agnostic map URLs.
 
* doi

Details on Digital Object Identifiers (DOI) can be found at https://doi.org.