Here's a simple file I made with working controller support. I have no special plugins or anything like that. Just the Chrome browser and a plugged in controller.
By the way, I'm using a PS3 controller with special drivers I downloaded that basically make the PC think it's an Xbox 360 controller. I only own a PS3, so that was my workaround.
Movement is with the D-Pad left and right and Jumping is set to the "A" button on a 360 controller.
I hope this helps.