I've written a small Aurelia application that binds to gamepad state here:
http://davismj.github.io/challenger/
I developed it using my Moga Power Pro in HID mode connected to my Windows 7 computer. However, it failed to detect the same gamepad when I opened it in Chrome 46 on my Nexus 5 (Marshmallow). I can confirm that the gamepad tester app also fails to detect the gamepad.
Is this a known issue? Is there a workaround? Can I report and track the issue somewhere?
I'm particularly surprised because the gamepad is not supported on windows, but well supported on Android on iOS.