Taking [denilson-sá's answer] further...
You need revision numbers to grab downloads. So first lookup the full version string from the following URL, adjusting parameters as needed:
For Chrome version 28 the full version string is 28.0.1500.71. Now go to https://omahaproxy.appspot.com and enter the full version string ("28.0.1500.71") into the Position Lookup box. Copy the Base Position number ("209842" in this case).