QUIC core library shim for RTCQuicTransport.

The RTCQuicTransport web API needs to use the underlying core QUIC
library. In order to use this API we need to create a shim of the
library that subclasses the QuicSession and QuicStream. This change
subclasses the QuicSession and has some basic implementation for
establishing a connection.

Bug: 874296
Change-Id: I63acd4913abc23733521157bd1aca4a3d1301c65
Reviewed-on: https://chromium-review.googlesource.com/1170125
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Henrik Boström <hbos@chromium.org>
Commit-Queue: Seth Hampson <shampson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594845}
12 files changed