Only copy the Elevation Service executable for Google Chrome builds.

BUG=180589,833687

Change-Id: I4af08c2124ea8857f2ad860c268913b87297da7a
Reviewed-on: https://chromium-review.googlesource.com/c/1373131
Reviewed-by: Sorin Jianu <sorin@chromium.org>
Reviewed-by: Greg Thompson <grt@chromium.org>
Commit-Queue: S. Ganesh <ganesh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616386}