Update platform/weborigin/OWNERS

Since origin_access_entry.* are files just to forward Blink calls
to equivalent services/network functions, let me add myself to the
OWNERS file as the network service side implementation author.

NOTRY: true
Change-Id: I9150caedc53e67ef9c18c37407fdbd85466bba43
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1616829Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Commit-Queue: Takashi Toyoshima <toyoshim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662516}

third_party/blink/renderer/platform/weborigin/OWNERS

 tsepez@chromium.org
 
+per-file origin_access_entry.*=toyoshim@chromium.org
+
 # TEAM: platform-architecture-dev@chromium.org
 # COMPONENT: Blink>Internals