touch_MouseScroll test uses thirteen gesture files that scroll. All scrolls
recorded should be done in a single motion (i.e. do not give a pause between
scroll movement). Having the scroll stop in the middle of the test would break
the test. The gesture files recorded are:

up_slow    - Scroll the mouse wheel up slowly to record multiple scrolls.
up_fast    - Scroll the mouse wheel up fast to record multiple scrolls.
up_1       - Scroll the mouse wheel up (one gear up) to record single scroll.
down_slow  - Scroll the mouse wheel down slowly to record scrolls.
down_fast  - Scroll the mouse wheel down fast to record multiple scrolls.
down_1     - Scroll the mouse wheel down (one gear down) to record single scroll.

To record horizontal scrolls, please emulate a mouse which has this feature and
start recodring the gesture files as:

right_slow    - Scroll the mouse ball right slowly to record multiple scrolls.
right_fast    - Scroll the mouse ball right fast to record multiple scrolls.
right_1       - Scroll the mouse ball right (one gear right) to record single scroll.
left_slow  - Scroll the mouse ball left slowly to record scrolls.
left_fast  - Scroll the mouse ball left fast to record multiple scrolls.
left_1     - Scroll the mouse ball left (one gear left) to record single scroll.

To position the cursor on center of page, center_cursor gesture file is used:

center_cursor - Use mouse to move the mouse pointer to center of the screen.
                As we do not know where the pointer would show up at the start
                of this test, hence to ensure that any starting cursor position
                will result in a centered cursor, move the cursor well into a
                corner of the screen and then move the cursor back to center of
                the test page. Do not pause the movement until pointer is at
                the center of page.