Add magchen@ to viz overlay owner list.

Change-Id: Ibc08b6a720494c7234104a8089b6ad9c580e774f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2528298Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Reviewed-by: weiliangc <weiliangc@chromium.org>
Commit-Queue: Maggie Chen <magchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826384}

components/viz/OWNERS

@@ -45,6 +45,7 @@ flackr@chromium.org
 ccameron@chromium.org
 dcastagna@chromium.org
 khushalsagar@chromium.org
+magchen@chromium.org
 
 # scheduling / begin frames
 sunnyps@chromium.org