Add myself to a few webapk/OWNERS

Change-Id: Ie4be68f2c648e0ea43d5494e7211df2b27a21d43
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2582903Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Commit-Queue: Glenn Hartmann <hartmanng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835359}

chrome/android/webapk/OWNERS

 hanxi@chromium.org
 pkotwicz@chromium.org
 yfriedman@chromium.org
+hartmanng@chromium.org

components/webapk/OWNERS

 hanxi@chromium.org
 pkotwicz@chromium.org
 yfriedman@chromium.org
+hartmanng@chromium.org