Migrate PrivetTrafficDetector to use NetworkConnectionTracker.

This migrates PrivetTrafficDetector from using
net::NetworkChangeNotifier to content::NetworkConnectionTracker, which
works with the network service enabled.

Bug: 859134
Change-Id: I06f2ecbe142bbed9a8772f69ab109b0c0dc32581
Reviewed-on: https://chromium-review.googlesource.com/1123681
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Robbie McElrath <rmcelrath@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574700}
2 files changed