base: Stop passing a non-const ref to ObserverListBase::Iterator.

base/observer_list_threadsafe.h

Index: base/observer_list_threadsafe.h
diff --git a/base/observer_list_threadsafe.h b/base/observer_list_threadsafe.h
index 1a6633372b8da5ac8589eef0f4dfe79f2ebaef7b..46ce88066931150c0bce56de59c5b9d7f373f9c6 100644
--- a/base/observer_list_threadsafe.h
+++ b/base/observer_list_threadsafe.h
@@ -199,6 +199,7 @@ class ObserverListThreadSafe
     scoped_refptr<base::MessageLoopProxy> loop;
     ObserverList<ObserverType> list;
 
+   private:
     DISALLOW_COPY_AND_ASSIGN(ObserverListContext);
   };
 
@@ -212,7 +213,6 @@ class ObserverListThreadSafe
   template <class Method, class Params>
   void NotifyWrapper(ObserverListContext* context,
       const UnboundMethod<ObserverType, Method, Params>& method) {
-
     // Check that this list still needs notifications.
     {
       base::AutoLock lock(list_lock_);
@@ -228,7 +228,7 @@ class ObserverListThreadSafe
     }
 
     {
-      typename ObserverList<ObserverType>::Iterator it(context->list);
+      typename ObserverList<ObserverType>::Iterator it(&context->list);
       ObserverType* obs;
       while ((obs = it.GetNext()) != NULL)
         method.Run(obs);