cros: Default to natural scrolling if the internal diplay is a touchscreen.

ash/display/display_manager.cc

Index: ash/display/display_manager.cc
diff --git a/ash/display/display_manager.cc b/ash/display/display_manager.cc
index 9ffa6c8408624ac2d33fd856ee37f051143be10a..7ab41fbfe662eb3257eeda7f024d49006f0a9e16 100644
--- a/ash/display/display_manager.cc
+++ b/ash/display/display_manager.cc
@@ -898,6 +898,7 @@ gfx::Display DisplayManager::CreateDisplayFromDisplayInfoById(int64 id) {
   new_display.SetScaleAndBounds(
       display_info.device_scale_factor(), gfx::Rect(bounds_in_native.size()));
   new_display.set_rotation(display_info.rotation());
+  new_display.set_touch_support(display_info.touch_support());
   return new_display;
 }