aura-x11: Avoid calling XISelectEvents on the root-window multiple times.

ui/aura/root_window_host_linux.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/aura/root_window_host_linux.h"
 
 #include <strings.h>
 #include <X11/cursorfont.h>
 #include <X11/extensions/Xfixes.h>
 #include <X11/extensions/XInput2.h>
@@ skipping 75 matching lines @@
 
   // Receive resize events for the root-window so |x_root_bounds_| can be
   // updated.
   XWindowAttributes attr;
   XGetWindowAttributes(display, root_window, &attr);
   if (!(attr.your_event_mask & StructureNotifyMask)) {
     XSelectInput(display, root_window,
                  StructureNotifyMask | attr.your_event_mask);
   }
 
-  XIEventMask evmask;
+  if (!base::MessagePumpForUI::HasXInput2())
+    return;
+
+  int num_masks = -1;
+  XIEventMask* current_mask = XIGetSelectedEvents(display, root_window,
+      &num_masks);
+  if (current_mask) {
+    XFree(current_mask);
+    return;
+  }
+
   unsigned char mask[XIMaskLen(XI_LASTEVENT)] = {};
   memset(mask, 0, sizeof(mask));
 
   XISetMask(mask, XI_HierarchyChanged);
 
   XISetMask(mask, XI_KeyPress);
   XISetMask(mask, XI_KeyRelease);
 
 #if defined(USE_XI2_MT)
   XISetMask(mask, XI_TouchBegin);
   XISetMask(mask, XI_TouchUpdate);
   XISetMask(mask, XI_TouchEnd);
 #endif
+
+  XIEventMask evmask;
   evmask.deviceid = XIAllDevices;
   evmask.mask_len = sizeof(mask);
   evmask.mask = mask;
 
   XISelectEvents(display, root_window, &evmask, 1);
 }
 
 // We emulate Windows' WM_KEYDOWN and WM_CHAR messages.  WM_CHAR events are only
 // generated for certain keys; see
 // http://msdn.microsoft.com/en-us/library/windows/desktop/ms646268.aspx.  Per
@@ skipping 784 matching lines @@
   return new RootWindowHostLinux(bounds);
 }
 
 // static
 gfx::Size RootWindowHost::GetNativeScreenSize() {
   ::Display* xdisplay = base::MessagePumpAuraX11::GetDefaultXDisplay();
   return gfx::Size(DisplayWidth(xdisplay, 0), DisplayHeight(xdisplay, 0));
 }
 
 }  // namespace aura