Extensions: Focus correct button on options dialog close.

Also fix some const references surfaced by presubmit.

Bug: 912026
Change-Id: If18dc61d8284c86cbec9f23e09286e9c5f666824
Reviewed-on: https://chromium-review.googlesource.com/c/1405459
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Hector Carmona <hcarmona@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622110}
5 files changed