Add dmazzoni to owners of ui/chromeos for accessibility features

BUG=none
R=dmazzoni@chromium.org, stevenjb@chromium.org

Review URL: https://codereview.chromium.org/343713002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@278122 0039d316-1c4b-4281-b951-d872f2087c98

ui/chromeos/OWNERS

@@ -2,3 +2,6 @@ derat@chromium.org
 jamescook@chromium.org
 oshima@chromium.org
 stevenjb@chromium.org
+
+# Accessibility
+per-file touch_exploration_controller*=dmazzoni@chromium.org