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Creates the various strings and constants required for the "Running in
Chrome" notification. The logic to trigger the notification when
appropriate, along with tests and the ability to act on the user
pressing on the notification, will be coming in following CLs.

Bug: 1068106
Change-Id: I5788a072e87768e55568e4b2a593554b51067d49
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2159467
Commit-Queue: Peter Conn <peconn@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#763299}