GitLab

Add an install warning for the case when an extension requests optional
permissions that are also listed as required permissions. Currently,
only do this for API permissions; a follow-up will handle host
permissions.

Bug: 859959
Change-Id: Ic9dc1a834e3e597aa12fe4136f4f087c6295400f
Reviewed-on: https://chromium-review.googlesource.com/c/1265118
Commit-Queue: Kelvin Jiang <kelvinjiang@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599379}