Add missing third_party/quic_trace/src files

These files got omitted because there was a stray .gitmodules file in
the directory which put git into a weird limbo state where it had no
_normal_ record (.gitmodules, .git/config, .git/modules) of that
directory being a module, but it also ignored any files put there.

TBR=mfoltz@chromium.org

Change-Id: I1d46db197e8dc9f0f01f02fbc5a4cc5f02f04eda