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This CL adds a handler for virtual URL re-write whenever the HTTPS
Previews is on and data saver is on. This will act on the committed URL
when it matches the lite page server URL.

This CL also adds UMA for server response and when a host is
blacklisted.

Bug: 921757,929969
Change-Id: I458f9bfb9b9c292a3f3a96065a7c6a9073ec2c23
Reviewed-on: https://chromium-review.googlesource.com/c/1488015
Commit-Queue: Ryan Sturm <ryansturm@chromium.org>
Reviewed-by: Robert Ogden <robertogden@chromium.org>
Cr-Commit-Position: refs/heads/master@{#635714}