The Network Service.

See https://bugs.chromium.org/p/chromium/issues/detail?id=598073

See the design doc
https://docs.google.com/document/d/1wAHLw9h7gGuqJNCgG1mP1BmLtCGfZ2pys-PdZQ1vg7M/edit?pref=2&pli=1#
