Added a command line switch to disable xinput2, enabled xinput2 by default

ui/events/devices/x11/device_data_manager_x11.h

Index: ui/events/devices/x11/device_data_manager_x11.h
diff --git a/ui/events/devices/x11/device_data_manager_x11.h b/ui/events/devices/x11/device_data_manager_x11.h
index c07aed4549845023b4a09957d8a921e5f9966e8f..bc36230845011deaaa46d9749a66f19a77c53652 100644
--- a/ui/events/devices/x11/device_data_manager_x11.h
+++ b/ui/events/devices/x11/device_data_manager_x11.h
@@ -359,6 +359,9 @@ class EVENTS_DEVICES_X11_EXPORT DeviceDataManagerX11
   // by valuator_lookup_[device_id][data_type].
   std::vector<int> valuator_lookup_[kMaxDeviceNum];
 
+  // Indicates if the user has disabled high precision scrolling support.
+  bool high_precision_scrolling_disabled_;
+
   // Index table to find the horizontal and vertical scroll valuator
   // numbers, scroll increments and scroll position.
   ScrollInfo scroll_data_[kMaxDeviceNum];