Consolidate win/x dispatchers

ui/aura/monitor_change_observer_x11.cc

Index: ui/aura/monitor_change_observer_x11.cc
diff --git a/ui/aura/monitor_change_observer_x11.cc b/ui/aura/monitor_change_observer_x11.cc
index 8618d1fdf110903a3d13ca7627a36ed6a56ea079..0181edfd116c99f044f235180bbfdda8c16c3dd1 100644
--- a/ui/aura/monitor_change_observer_x11.cc
+++ b/ui/aura/monitor_change_observer_x11.cc
@@ -55,13 +55,13 @@ MonitorChangeObserverX11::~MonitorChangeObserverX11() {
       WindowDispatcherDestroying(x_root_window_);
 }
 
-base::MessagePumpDispatcher::DispatchStatus
-MonitorChangeObserverX11::Dispatch(XEvent* event) {
+base::DispatchStatus MonitorChangeObserverX11::Dispatch(
+    const base::NativeEvent& event) {
   if (event->type - xrandr_event_base_ == RRScreenChangeNotify) {
     NotifyMonitorChange();
-    return base::MessagePumpDispatcher::EVENT_PROCESSED;
+    return base::EVENT_PROCESSED;
   }
-  return base::MessagePumpDispatcher::EVENT_IGNORED;
+  return base::EVENT_IGNORED;
 }
 
 void MonitorChangeObserverX11::NotifyMonitorChange() {