Implemented smooth scrolling using xinput2 in X11.

ui/events/platform/x11/x11_event_source.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_event_source.h"
 
 #include <X11/extensions/XInput2.h>
 #include <X11/X.h>
 #include <X11/Xlib.h>
 #include <X11/XKBlib.h>
@@ skipping 116 matching lines @@
     have_cookie = true;
   }
 
   uint32_t action = PlatformEventSource::DispatchEvent(xevent);
   if (xevent->type == GenericEvent &&
       xevent->xgeneric.evtype == XI_HierarchyChanged) {
     ui::UpdateDeviceList();
     hotplug_event_handler_->OnHotplugEvent();
   }
 
+  if ((xevent->type == EnterNotify || xevent->type == LeaveNotify) &&
+      xevent->xcrossing.mode == NotifyNormal) {
+    // Clear stored scroll data
+    ui::DeviceDataManagerX11::GetInstance()->InvalidateScrollClasses();
+  }
+
   if (have_cookie)
     XFreeEventData(xevent->xgeneric.display, &xevent->xcookie);
   return action;
 }
 
 void X11EventSource::StopCurrentEventStream() {
   continue_stream_ = false;
 }
 
 void X11EventSource::OnDispatcherListChanged() {
   if (!hotplug_event_handler_) {
     hotplug_event_handler_.reset(new X11HotplugEventHandler());
     // Force the initial device query to have an update list of active devices.
     hotplug_event_handler_->OnHotplugEvent();
   }
 }
 
 }  // namespace ui