chromium/chrome/test/data/mac_installer/requestSample.xml

<?xml version="1.0" encoding="UTF-8"?>
<request protocol="3.0" version="KeystoneAgent-1.99.4.0">

  <os platform="mac" version="10.11" arch="x86_64h" sp="10.11.4_x86_64h"></os>

  <app appid="com.google.Chrome" version="1.1.1.1" lang="en-us">

    <updatecheck></updatecheck>

  </app>

</request>