Add gsathya to top-level OWNERS

R=bmeurer@chromium.org, gsathya@chromium.org, yangguo@chromium.org

Review-Url: https://codereview.chromium.org/2591613003 .
Cr-Commit-Position: refs/heads/master@{#41901}

OWNERS

@@ -8,6 +8,7 @@ cbruni@chromium.org
 danno@chromium.org
 epertoso@chromium.org
 franzih@chromium.org
+gsathya@chromium.org
 hablich@chromium.org
 hpayer@chromium.org
 ishell@chromium.org