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

content/browser/service_worker/embedded_worker_instance.cc

Index: content/browser/service_worker/embedded_worker_instance.cc
diff --git a/content/browser/service_worker/embedded_worker_instance.cc b/content/browser/service_worker/embedded_worker_instance.cc
index 1b15acfe14637141a809291fe743ab5d8fdf394c..e7b27c3057405be34b72617e93bf598b39a2ef11 100644
--- a/content/browser/service_worker/embedded_worker_instance.cc
+++ b/content/browser/service_worker/embedded_worker_instance.cc
@@ -389,7 +389,7 @@ void EmbeddedWorkerInstance::OnPausedAfterDownload() {
 }
 
 bool EmbeddedWorkerInstance::OnMessageReceived(const IPC::Message& message) {
-  ListenerList::Iterator it(listener_list_);
+  ListenerList::Iterator it(&listener_list_);
   while (Listener* listener = it.GetNext()) {
     if (listener->OnMessageReceived(message))
       return true;