Reland "[omnibox] Steady State Elisions - Enable flag by default"

This is a reland of 8967c49035448553e1554633b84d460326b6c10a

We are re-enabling these by default.

Original change's description:
> [omnibox] Steady State Elisions - Enable flag by default
>
> To prepare for launch, enabling these by default on tip of tree.
>
> Bug: 842236
> Change-Id: I0d40540fcfb6262238670ccfbcbe3d7f371e05e2
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1577488
> Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
> Commit-Queue: Tommy Li <tommycli@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#652916}

Bug: 842236
Change-Id: I55a77cbf871dbe0114180ff81bce0bd8129940a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1677024
Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Commit-Queue: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672210}
1 file changed