Implemented smooth scrolling using xinput2 in X11.

ui/events/devices/x11/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/devices/x11/touch_factory_x11.h"
 
 #include <stddef.h>
 #include <X11/Xatom.h>
 #include <X11/cursorfont.h>
 #include <X11/extensions/XInput.h>
@@ skipping 203 matching lines @@
   unsigned char mask[XIMaskLen(XI_LASTEVENT)];
   memset(mask, 0, sizeof(mask));
 
   XISetMask(mask, XI_TouchBegin);
   XISetMask(mask, XI_TouchUpdate);
   XISetMask(mask, XI_TouchEnd);
 
   XISetMask(mask, XI_ButtonPress);
   XISetMask(mask, XI_ButtonRelease);
   XISetMask(mask, XI_Motion);
+  // HierarchyChanged and DeviceChanged allow X11EventSource to still pick up
+  // these events.
+  XISetMask(mask, XI_HierarchyChanged);
+  XISetMask(mask, XI_DeviceChanged);
 #if defined(OS_CHROMEOS)
   // XGrabKey() must be replaced with XI2 keyboard grab if XI2 key events are
   // enabled on desktop Linux.
   if (base::SysInfo::IsRunningOnChromeOS()) {
     XISetMask(mask, XI_KeyPress);
     XISetMask(mask, XI_KeyRelease);
   }
 #endif
 
   XIEventMask evmask;
@@ skipping 103 matching lines @@
       std::find_if(touchscreens.begin(), touchscreens.end(),
                    [device_id](const TouchscreenDevice& touchscreen) {
                      return touchscreen.id == device_id;
                    });
   // Internal displays will have a vid and pid of 0. Ignore them.
   if (it != touchscreens.end() && it->vendor_id && it->product_id)
     touchscreen_ids_.insert(std::make_pair(it->vendor_id, it->product_id));
 }
 
 }  // namespace ui