touch_BackFwdTest test uses two gesture files that long-scroll horizontally.
All scrolls recorded should be unaccelerated and done in a single motion
(i.e. do not lift fingers and continue to scroll). Having the scroll stop
in the middle of the test would break the test.

The gesture files for each device recorded are:
<DEVICE NAME>_touchpad_Touch ID_two-finger-longswipe-back  - Two finger long
scroll on touchpad to navigate back.
<DEVICE NAME>_touchpad_Touch ID_two-finger-longswipe-fwd  - Two finger long
scroll on touchpad to navigate forward.