If others out there have had a problem with the very sneaky "Downtango" download app that just WON'T disappear, even after uninstalling, here's what to do.
Copy and paste "chrome://plugins/" in your address bar
Once you're in plugins, search for an anonymous plugin that just says:
"browser plugin - Version: 1, 0, 0, 1"
That's your sneaky "Downtango" plugin.
Click "disable" and you're done.
You can now download normally again.
As for the downtango toolbar, which I have heard others have had problems with, I can't help - I have no experience with it.
What Google can do for us is to give us a simple option to totally delete certain plugins, and provide info at a click to find out what they do. Google should also never allow a plugin that does not leave either the publisher or the product name somewhere it can be easily recognized. That's simply polite!
Good luck, Chromers!