Refcount touch tracking ids to prevent freeing them too early.

ui/events/cocoa/events_mac.mm

Index: ui/events/cocoa/events_mac.mm
diff --git a/ui/events/cocoa/events_mac.mm b/ui/events/cocoa/events_mac.mm
index 74c28a23767fd23a54e3cfd224f23391647b9a25..43d941c776c3e6df581ca2064442330c5e5d4cd6 100644
--- a/ui/events/cocoa/events_mac.mm
+++ b/ui/events/cocoa/events_mac.mm
@@ -148,6 +148,10 @@ void ReleaseCopiedNativeEvent(const base::NativeEvent& event) {
   [event release];
 }
 
+void IncrementTouchIdRefCount(const base::NativeEvent& native_event) {
+  NOTIMPLEMENTED();
+}
+
 void ClearTouchIdIfReleased(const base::NativeEvent& native_event) {
   NOTIMPLEMENTED();
 }