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

ui/events/devices/x11/touch_factory_x11.h

Index: ui/events/devices/x11/touch_factory_x11.h
diff --git a/ui/events/devices/x11/touch_factory_x11.h b/ui/events/devices/x11/touch_factory_x11.h
index b5bf027bd8657cd4d614161206486f39155a65a6..e42043b99ae471312b0b8f8dbed09d7e5dea20e2 100644
--- a/ui/events/devices/x11/touch_factory_x11.h
+++ b/ui/events/devices/x11/touch_factory_x11.h
@@ -67,10 +67,6 @@ class EVENTS_DEVICES_EXPORT TouchFactory {
   // isn't one already, allocates a new slot ID and sets up the mapping.
   int GetSlotForTrackingID(uint32 tracking_id);
 
-  // Increases the number of times |ReleaseSlotForTrackingID| needs to be called
-  // on a given tracking id before it will actually be released.
-  void AcquireSlotForTrackingID(uint32 tracking_id);
-
   // Releases the slot ID mapping to tracking ID.
   void ReleaseSlotForTrackingID(uint32 tracking_id);
 
@@ -133,10 +129,6 @@ class EVENTS_DEVICES_EXPORT TouchFactory {
   // Touch screen <vid, pid>s.
   std::set<std::pair<int, int> > touchscreen_ids_;
 
-  // Maps from a tracking id to the number of times |ReleaseSlotForTrackingID|
-  // must be called before the tracking id is released.
-  std::map<uint32, int> tracking_id_refcounts_;
-
   // Maximum simultaneous touch points supported by device. In the case of
   // devices with multiple digitizers (e.g. multiple touchscreens), the value
   // is the maximum of the set of maximum supported contacts by each individual