Reland of NQE servicification of data saver proxy

Use network quality tracker instead of network quality estimator (NQE)
to obtain network quality in data reduction proxy component.

Network quality tracker can provide network service when network
service is enabled as well as when network service is disabled.

data_reduction_proxy_service.h receives network quality
estimates on UI thread from network quality tracker.
On receiving estimates, it posts them to d_r_p_io_data
which lives on IO thread, and consumes the estimates.

PS#2 is the original CL that got reverted.

Bug: 819244
Cq-Include-Trybots: luci.chromium.try:linux_mojo
Change-Id: Id9f28abaea42a7eb55dd3647c88d13a427a4e5ae
TBR: xunjieli@chromium.org, sky@chromium.org, ryansturm@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/1174698
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583065}
27 files changed