Tab Search: add yuhengh to OWNERS

Bug: 1099917
Change-Id: Ie496c68ea5fbcc05eb803da4a74fcd3f2eaadd88
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2392764Reviewed-by: Thomas Lukaszewicz <tluk@chromium.org>
Commit-Queue: Thomas Lukaszewicz <tluk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804354}

chrome/browser/ui/webui/tab_search/OWNERS

 robliao@chromium.org
 tluk@chromium.org
+yuhengh@chromium.org
 
 per-file *.mojom=set noparent
 per-file *.mojom=file://ipc/SECURITY_OWNERS