[omnibox chrome:omnibox] Use `rem` instead of `px` for font-size units

Bug: 891303
Change-Id: Ibeaf710631e305e055e38f73cd049b24853b5a76
Reviewed-on: https://chromium-review.googlesource.com/c/1407090
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624218}
3 files changed