[snapshot] Add delphick to OWNERS

Change-Id: I73532f4cba643032c5fad6e9bca70c901bf71f85
Reviewed-on: https://chromium-review.googlesource.com/c/1491513
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59904}

src/snapshot/OWNERS

 set noparent
 
+delphick@chromium.org
 jgruber@chromium.org
 petermarshall@chromium.org
 verwaest@chromium.org