Invoke cursor-hiding logic on touch for Windows

Continue to invoke cursor-hiding logic on touch
for Windows even though the OS hides the cursor
for us. The reason is that this code path is
needed in order to call
RenderWidgetHostViewAura::
    NotifyRendererOfCursorVisibilityState()
in order for the renderer to know to suppress
generation of synthetic mousemove events
while touch scrolling. This avoids unwanted
hover effects from being invoked when the
cursor is not visible.

To avoid regressions in behavior (such as
the one mentioned in
https://codereview.chromium.org/56053004),
make the cursor state global among all
root windows. This is done in
https://codereview.chromium.org/111043002/.

BUG=322250
TEST=To be added later (crbug.com/328549)
R=sky@chromium.org

Review URL: https://codereview.chromium.org/82463002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240976 0039d316-1c4b-4281-b951-d872f2087c98
Uprev branch to 1750 to make the branch point more obvious.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240978 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240978