Reland "Make NetworkConnectionTracker survive network service crashes and restarts"

This reverts commit 197e9188dc5be69cb34e1ebd67f86a1146439367.

Reason for revert: There is a racy test expectation that causes the test to timeout.
This CL fixes the test.

Bug: 862883, 821009
Change-Id: I1cb4d8db6ea3f5c683f95bcc3187f6c6b4d6fdbd
Reviewed-on: https://chromium-review.googlesource.com/1135290
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Helen Li <xunjieli@chromium.org>
Commit-Queue: Helen Li <xunjieli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574642}
6 files changed