QUIC core library shim for streams.

This includes subclassing the QuicStream to be used by the RTCQuicStream
web API. It is a very basic implementation for the stream, and does not
include the functionality that will be needed for reaading and writing.

Bug: 874296
Change-Id: I25b69c06986cd68728b966ec28b67684ace5a87b
Reviewed-on: https://chromium-review.googlesource.com/1199765
Commit-Queue: Seth Hampson <shampson@chromium.org>
Reviewed-by: Henrik Boström <hbos@chromium.org>
Reviewed-by: Harald Alvestrand <hta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594894}
9 files changed