[omnibox] Add about:flag for OmniboxAlternateMatchDescriptionSeparator

Bug: 955585
Change-Id: Ifbb7814a2087c1a77f462836aabffbbe41a2e14e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1581987
Reviewed-by: Orin Jaworski <orinj@chromium.org>
Commit-Queue: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653756}
5 files changed