Add support for dependent types in FOR_EACH_OBSERVER

base/observer_list.h

Index: base/observer_list.h
diff --git a/base/observer_list.h b/base/observer_list.h
index 31564212e05f15262af24a3b2d07bd026055fa32..afe1f46cd6e31bfaa0456cec8614fd73f3cd0e1e 100644
--- a/base/observer_list.h
+++ b/base/observer_list.h
@@ -236,8 +236,8 @@ class ObserverList : public ObserverListBase<ObserverType> {
 #define FOR_EACH_OBSERVER(ObserverType, observer_list, func)             \
   do {                                                                   \
     if ((observer_list).might_have_observers()) {                        \
-      base::ObserverListBase<ObserverType>::Iterator it_inside_observer_macro( \
-          &observer_list);                                               \
+      typename base::ObserverListBase<ObserverType>::Iterator            \
+          it_inside_observer_macro(&observer_list);                      \
       ObserverType* obs;                                                 \
       while ((obs = it_inside_observer_macro.GetNext()) != nullptr)      \
         obs->func;                                                       \