Adding smaier@ to owners of android_async_task and ProGuard flags

Change-Id: I6e3603ad89eca72a3cdd481dfb1667105b6ef0ed
Reviewed-on: https://chromium-review.googlesource.com/1169128Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Commit-Queue: Sam Maier <smaier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582239}

chrome/android/java/OWNERS

 per-file *.flags=agrieve@chromium.org
+per-file *.flags=smaier@chromium.org
 per-file *.grd*=twellington@chromium.org

third_party/android_async_task/OWNERS

 agrieve@chromium.org
 hartmanng@chromium.org
+smaier@chromium.org
 torne@chromium.org
 wnwen@chromium.org