Remove the GoogleURLTracker infobar functionality entirely.

Remove the GoogleURLTracker infobar functionality entirely.

Now instead of prompting the user which search domain they would like when they
perform a search after Chrome has detected a new search domain, we just accept
what searchdomaincheck tells us immediately.

If the domain changes with existing search pages open, we don't reload those
pages on the new domain, as we did with the infobar if you clicked the button to
change domains; doing so could interrupt what the user is doing and will
certainly be surprising.  We just allow future searches to use the new domain.

BUG=421174
TEST=A machine moved among different countries should automatically change search domains to the local domains (on network switch or Chrome restart) without prompting the user

Review URL: https://codereview.chromium.org/808253006

Cr-Commit-Position: refs/heads/master@{#310395}