[omnibox] Configure OpenSearch requests with timeout and retry

This CL makes OpenSearch description document fetching more robust
by timing out old failed requests and retrying requests that would
otherwise silently fail due to network change.

Bug: 956689
Change-Id: I26e21194ea8911916b7766b3a6eb47d6d35643c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1688437
Commit-Queue: Orin Jaworski <orinj@chromium.org>
Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676536}
1 file changed