Expose OmniboxUIExperimentMaxAutocompleteMatches flag on iOS.

Exposes the OmniboxUIExperimentMaxAutocompleteMatches flag on iOS flags
page. Unfortunately, there seems to be no good way to share flags with
iOS at the moment, so this involves a lot of copy-paste.

Also extend maximum numbers of rows in UI implementation to 12 to
prevent crashes when this flag is used.

Bug: 908478
Change-Id: I5347400289cd10ac2ae735e9ed6cb930c6a0d405
Reviewed-on: https://chromium-review.googlesource.com/c/1425722
Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Auto-Submit: Stepan Khapugin <stkhapugin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625180}
4 files changed