[omnibox] Set a minimum size for OmniboxMatchCellView.

When downsizing the page, we scale/snap to the min size instead of to 0.

The text indent is used as the min width because when downsizing, we want the suggestion buttons to remain aligned with where the suggestion text used to be.

Before: http://screencast.googleplex.com/cast/NDg1NjA3NzcwMjEzNTgwOHxjZTY2ZTU4Ny0xZQ
After: https://screencast.googleplex.com/cast/NjQ1MzE5NzE2MDg0MTIxNnw0OWU2YjAzNS0yNg
Change-Id: I1d5c7d5dcc1d027b0c41d6601412256d54a09151
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6825390
Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Reviewed-by: Khalid Peer <khalidpeer@chromium.org>
Commit-Queue: Hannah Collins <hannahrogers@google.com>
Cr-Commit-Position: refs/heads/main@{#1498509}