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

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index f983210a196f056da8228f98e0b258610174d033..7147c43a438a769f5026ec8b8c342edc11baa7e4 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -1722,10 +1722,8 @@ void RenderThreadImpl::OnChannelError() {
 }
 
 bool RenderThreadImpl::OnControlMessageReceived(const IPC::Message& msg) {
-  base::ObserverListBase<RenderThreadObserver>::Iterator it(&observers_);
-  RenderThreadObserver* observer;
-  while ((observer = it.GetNext()) != nullptr) {
-    if (observer->OnControlMessageReceived(msg))
+  for (auto& observer : observers_) {
+    if (observer.OnControlMessageReceived(msg))
       return true;
   }