Remove usage of base::ObserverList<T>::Iter::GetNext() in //ui.

ui/views/mus/pointer_watcher_event_router.cc

Index: ui/views/mus/pointer_watcher_event_router.cc
diff --git a/ui/views/mus/pointer_watcher_event_router.cc b/ui/views/mus/pointer_watcher_event_router.cc
index 998c4cf0d61c6f3a77a654c2aae568275a6b4d0c..6d0217b3e6fcfc8bd8ed90878cd07db027da27b2 100644
--- a/ui/views/mus/pointer_watcher_event_router.cc
+++ b/ui/views/mus/pointer_watcher_event_router.cc
@@ -17,14 +17,7 @@ namespace {
 
 bool HasPointerWatcher(
     base::ObserverList<views::PointerWatcher, true>* observer_list) {
-  if (!observer_list->might_have_observers())
-    return false;
-
-  // might_have_observers() returned true, see if there really are any
-  // observers. The only way to truly know is to use an Iterator and see if it
-  // has at least one observer.
-  base::ObserverList<PointerWatcher>::Iterator iterator(observer_list);
-  return !!iterator.GetNext();
+  return observer_list->begin() != observer_list->end();
 }
 
 }  // namespace