Fix direction of horizontal scroll when tilting the scroll wheel on Linux Aura

BUG=342926
TEST=Manual, see bug

Review URL: https://codereview.chromium.org/187333004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255142 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255142