GitLab

Update the chrome://extensions page to use the developerPrivate api in order
to show the permissions prompt.
Also convert the function to a UIThreadExtensionFunction, and update it to
(if possible) use the new app info dialog.

BUG=461039

Review URL: https://codereview.chromium.org/1008973002

Cr-Commit-Position: refs/heads/master@{#320801}