Fix network quality estimator tests
(1) Enabling the tests that were disabled on Windows:
Windows requires nested classes to have EXPORT macros.
(2) Enabling the flaky test:
Sometimes the RTT observation may be equal to
base::TimeDelta() because of low timer granularity.
This was causing one of the network quality estimator test to flake.
BUG=504058,492410
Review URL: https://codereview.chromium.org/1210743002
Cr-Commit-Position: refs/heads/master@{#336175}
2 files changed
