Refcount touch tracking ids to prevent freeing them too early.

ui/events/events_stub.cc

Index: ui/events/events_stub.cc
diff --git a/ui/events/events_stub.cc b/ui/events/events_stub.cc
index dbd359660e9649ece932a999602336048e6e2f30..20d13e5d644f034c7e93cfa16a8e0a2236e7d501 100644
--- a/ui/events/events_stub.cc
+++ b/ui/events/events_stub.cc
@@ -12,7 +12,7 @@
 namespace ui {
 
 // Stub implementations of platform-specific methods in events_util.h, built
-// on platform sthat currently do not have a complete implementation of events.
+// on platforms that currently do not have a complete implementation of events.
 
 void UpdateDeviceList() {
   NOTIMPLEMENTED();
@@ -69,6 +69,10 @@ base::NativeEvent CopyNativeEvent(const base::NativeEvent& event) {
 void ReleaseCopiedNativeEvent(const base::NativeEvent& event) {
 }
 
+void IncrementTouchIdRefCount(const base::NativeEvent& native_event) {
+  NOTIMPLEMENTED();
+}
+
 void ClearTouchIdIfReleased(const base::NativeEvent& native_event) {
   NOTIMPLEMENTED();
 }