Make the Automatic detection of "Enable touch events" work in Linux

ui/events/platform/x11/x11_hotplug_event_handler.cc

 // Copyright 2014 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 "ui/events/platform/x11/x11_hotplug_event_handler.h"
 
 #include <X11/Xatom.h>
 #include <X11/extensions/XInput.h>
 #include <X11/extensions/XInput2.h>
 
@@ skipping 227 matching lines @@
     const DisplayState& display_state,
     scoped_refptr<base::TaskRunner> reply_runner,
     const TouchscreenDeviceCallback& callback) {
   std::vector<TouchscreenDevice> devices;
   if (display_state.mt_position_x == None ||
       display_state.mt_position_y == None)
     return;
 
   std::set<int> no_match_touchscreen;
   for (const DeviceInfo& device_info : device_infos) {
-    if (!device_info.enabled || device_info.use != XIFloatingSlave)
-      continue;  // Assume all touchscreens are floating slaves
+    if (!device_info.enabled || (device_info.use != XIFloatingSlave
+        && device_info.use != XISlavePointer))
+      continue;
 
     double max_x = -1.0;
     double max_y = -1.0;
     bool is_direct_touch = false;
 
     for (const ValuatorClassInfo& valuator : device_info.valuator_class_infos) {
       if (display_state.mt_position_x == valuator.label) {
         // Ignore X axis valuator with unexpected properties
         if (valuator.number == 0 && valuator.mode == Absolute &&
             valuator.min == 0.0) {
@@ skipping 87 matching lines @@
   base::WorkerPool::PostTask(FROM_HERE,
                              base::Bind(&HandleHotplugEventInWorker,
                                         device_infos,
                                         display_state,
                                         base::ThreadTaskRunnerHandle::Get(),
                                         callbacks),
                              true /* task_is_slow */);
 }
 
 }  // namespace ui