ORIGINAL: sensei
IMO ailerons will provide lift only if they are part of the airfoil of the wing, the chord would be then from the leading edge of the wing to the trailing edge of the aileron.
If the ailerons are flat with no airfoil profile (as on some sports planes and fun fly's), the chord would then be from the leading edge of the wing to the hinge line as the aileron being parallel top and bottom would provide no lift.
Can't think of many airplanes where the ailerons aren't part of the wing's airfoil, but a couple come to mind. The Stuka and the JU52 both fit the description.
The ailerons on those birds contribute lift and drag.
And to the point of this discussion, their area is included in the area of the wing by most AEs when talking about the simpler aspects of the airplanes. Can you think of any outside part of any airplane doesn't contribute to drag and can't provide lift?