Add a StreamChannelCompleter class.

This is by analogy with StreamCompleter and StreamSinkCompleter in the
async package, and is in fact implemented using them.

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//1631103002 .
4 files changed
tree: d5423f70d42406c6b5a01cbcbc25f2ed6afc3283
  1. pkgs/