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

ui/events/devices/x11/ui_events_devices_x11_switches.cc

+// Copyright (c) 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "build/build_config.h"
+#include "ui/events/devices/x11/ui_events_devices_x11_switches.h"
+
+namespace switches {
+
+#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_CHROMEOS)
+// Disables high precision scrolling in X11
+const char kDisableHighPrecisionScrolling[] =
+    "disable-high-precision-scrolling";
+#endif
+
+}  // namespace switches