GitLab

Prior to this change, enabling Reverse scrolling would meant that
swiping up would cause the page to move up, and vice versa. This CL
corrects that so that:

* Turn off Reverse (swipe up to move the page up).
* Turn on Reverse (swipe up to move the page down).

This is fixed by setting the "natural_scroll" pref to true if
"Reverse Scrolling" is enabled, and the "natural_scroll" pref to false
if "Reverse Scrolling" is disabled, instead of the opposite as it was
previously.

Fixed: 1109966
Change-Id: Id60df73f421992dce893339b6efaac0941ef9110
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2321235
Commit-Queue: Regan Hsu <hsuregan@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792558}