None of the solutions worked for me, the username and password inputs were still being populated and given the yellow background.
So I asked myself, "How does Chrome determine what should be autofilled on a given page?"
"Does it look for input ids, input names? Form ids? Form action?"
Through my experimentation with the username and the password inputs, there were only two ways I found that would cause Chrome to not be able to find the fields that should be autofilled:
1) Put the password input ahead of the text input.
2) Give them the same name and id ... or no name and id.
After the page loads, with javascript you can either change the order of the inputs on the page, or dynamically give them their name and id ...
And Chrome doesn't know what hit it ... autocomplete stays off.
Crazy hack, I know. But it's working for me.
Chrome 34.0.1847.116, OSX 10.7.5