[ios] Improves Password InfobarModal A11y.

Bug: 961343
Change-Id: I292fb04c40117e47d3e1a45bb0a102debef9ed2f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1616973
Reviewed-by: Peter Lee <pkl@chromium.org>
Reviewed-by: Chris Lu <thegreenfrog@chromium.org>
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661495}
4 files changed