This CL integrates recent Chromium changes that were merged
into https://github.com/devsisters/libquic/tree/master.
It also performs minor cleanup, such as removing accidental
usage of Chromium logging symbols (e.g. LOG(INFO),
LOG(ERROR) instead of LOG(LS_INFO), LOG(LS_ERROR)) and
using Chromium's scoped_ptr instead of rtc::scoped_ptr.
BUG=
Review URL: https://codereview.webrtc.org/1834233002
Cr-Commit-Position: refs/heads/master@{#12146}
