For Internals>Network>HTTP2

See:
  http://httpwg.org/http-extensions/origin-frame.html

Compared to 421, ORIGIN removes a RT, allows a definitive set of origins to be associated with a connection, and has clearer semantics.

See also #546991. If you have feedback on the spec, please bring it up; the current version seems to have broad support, but if there are specific needs that Chrome has, we'd love to hear them.