Revert of Don't refcount tracking id -> slot id mapping.

ui/events/x/events_x.cc

Index: ui/events/x/events_x.cc
diff --git a/ui/events/x/events_x.cc b/ui/events/x/events_x.cc
index 6c83976b32e4b3409b5dbf75fb90c0bf9acd97d0..6678f01dac7983e7a637ae2c6a339409afb16081 100644
--- a/ui/events/x/events_x.cc
+++ b/ui/events/x/events_x.cc
@@ -739,6 +739,18 @@
   delete event;
 }
 
+void IncrementTouchIdRefCount(const base::NativeEvent& xev) {
+  ui::DeviceDataManagerX11* manager = ui::DeviceDataManagerX11::GetInstance();
+  double tracking_id;
+  if (!manager->GetEventData(
+          *xev, ui::DeviceDataManagerX11::DT_TOUCH_TRACKING_ID, &tracking_id)) {
+    return;
+  }
+
+  ui::TouchFactory* factory = ui::TouchFactory::GetInstance();
+  factory->AcquireSlotForTrackingID(tracking_id);
+}
+
 void ClearTouchIdIfReleased(const base::NativeEvent& xev) {
   ui::EventType type = ui::EventTypeFromNative(xev);
   if (type == ui::ET_TOUCH_CANCELLED ||