Adding support for sending horizonatal mouse wheel information in Chrome ASH on Windows 8.

Currently using the horizontal mouse wheel also causes vertical scrolling. With this change we send over
a flag in the mouse messages which indicates if horizontal scrolling is being done and if yes we create
the right MouseWheelEvent instance.

BUG=332797
R=cpu@chromium.org, jschuh@chromium.org, sky@chromium.org, cpu

Review URL: https://codereview.chromium.org/141953014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246730 0039d316-1c4b-4281-b951-d872f2087c98
4 files changed