gentoo-overlay/www-client/chromium/files/chromium-browser.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE default-apps SYSTEM "gnome-da-list.dtd">
<default-apps>
  <web-browsers>
    <web-browser>
      <name>Chromium</name>
      <executable>chromium-browser</executable>
      <command>chromium-browser %s</command>
      <icon-name>chromium-browser</icon-name>
      <run-in-terminal>false</run-in-terminal>
    </web-browser>
  </web-browsers>
</default-apps>