[client-hints] Add aarontag@ to client hint owners

Bug: 924047
Change-Id: Iaffbf6fd73993ea4db3cdc89f94ca9dc3710b86f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2307090Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Aaron Tagliaboschi <aarontag@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790334}

chrome/browser/client_hints/OWNERS

 yoavweiss@chromium.org
 tbansal@chromium.org
 ryansturm@chromium.org
+aarontag@chromium.org
 
 # For IPC security review
 per-file *.mojom=set noparent

components/client_hints/OWNERS

 yoavweiss@chromium.org
 tbansal@chromium.org
 ryansturm@chromium.org
+aarontag@chromium.org
 
 # COMPONENT: Blink>Loader