r545122 landed for this bug (CL linked to a wrong bug!)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/92c5ab40e202ed3252c73578f46e117bdd5b7465

commit 92c5ab40e202ed3252c73578f46e117bdd5b7465
Author: Mohsen Izadi <mohsen@chromium.org>
Date: Thu Mar 29 05:23:31 2018

Honor overscroll-behavior CSS property in new gesture-nav UI

When overscroll-behavior-x for the root element of a page is set to
anything other than 'auto', gesture-nav should not start on the page.

Similarly, when overscroll-behavior-y for the root element of a page is
set to anything other than 'auto', pull-to-refresh should not start on
the page.

BUG= 800074 ,742510
TEST=GestureNavSimpleTest.* in content_unittests

Change-Id: I86cf2f50c5ceb6613dc293c1fd32ca2cfff4daa2
Reviewed-on: https://chromium-review.googlesource.com/981127
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Mohsen Izadi <mohsen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546736}
[modify] https://crrev.com/92c5ab40e202ed3252c73578f46e117bdd5b7465/content/browser/web_contents/aura/gesture_nav_simple.cc
[modify] https://crrev.com/92c5ab40e202ed3252c73578f46e117bdd5b7465/content/browser/web_contents/aura/gesture_nav_simple.h
[add] https://crrev.com/92c5ab40e202ed3252c73578f46e117bdd5b7465/content/browser/web_contents/aura/gesture_nav_simple_unittest.cc
[modify] https://crrev.com/92c5ab40e202ed3252c73578f46e117bdd5b7465/content/test/BUILD.gn