Build fix linux aura without USE_XI2_MT.

ui/events/x/touch_factory_x11.cc

 // Copyright (c) 2012 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/x/touch_factory_x11.h"
 
 #include <X11/cursorfont.h>
 #include <X11/extensions/XInput.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/extensions/XIproto.h>
@@ skipping 73 matching lines @@
 
 #if !defined(USE_XI2_MT)
   // NOTE: The new API for retrieving the list of devices (XIQueryDevice) does
   // not provide enough information to detect a touch device. As a result, the
   // old version of query function (XListInputDevices) is used instead.
   // If XInput2 is not supported, this will return null (with count of -1) so
   // we assume there cannot be any touch devices.
   // With XI2.1 or older, we allow only single touch devices.
   XDeviceList dev_list =
       DeviceListCacheX::GetInstance()->GetXDeviceList(display);
+  Atom xi_touchscreen = XInternAtom(display, XI_TOUCHSCREEN, false);
   for (int i = 0; i < dev_list.count; i++) {
-    if (dev_list[i].type) {
-      XScopedString devtype(XGetAtomName(display, dev_list[i].type));
-      if (devtype.string() && !strcmp(devtype.string(), XI_TOUCHSCREEN)) {
-        touch_device_lookup_[dev_list[i].id] = true;
-        touch_device_list_[dev_list[i].id] = false;
-        touch_device_available_ = true;
-      }
+    if (dev_list[i].type == xi_touchscreen) {
+      touch_device_lookup_[dev_list[i].id] = true;
+      touch_device_list_[dev_list[i].id] = false;
+      touch_device_available_ = true;
     }
   }
 #endif
 
   // Instead of asking X for the list of devices all the time, let's maintain a
   // list of pointer devices we care about.
   // It should not be necessary to select for slave devices. XInput2 provides
   // enough information to the event callback to decide which slave device
   // triggered the event, thus decide whether the 'pointer event' is a
   // 'mouse event' or a 'touch event'.
@@ skipping 133 matching lines @@
        iter != devices.end(); ++iter) {
     DCHECK(*iter < touch_device_lookup_.size());
     touch_device_lookup_[*iter] = true;
     touch_device_list_[*iter] = true;
   }
   touch_device_available_ = true;
   touch_events_disabled_ = false;
 }
 
 }  // namespace ui