Add a feature to limit DSE preconnect to Google only

This feature allows us to experiment on Google without possibly creating
issues with non-Google DSEs. This will hopefully prevent problems or
regressions with other search engines.

Bug: 1036489
Change-Id: I688338981460ab3b532577b1bc176fde89fd3e96
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2020534
Reviewed-by: Robert Ogden <robertogden@chromium.org>
Commit-Queue: Ryan Sturm <ryansturm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735179}
3 files changed