Replace FOR_EACH_OBSERVER in c/b/chromeos with range-based for

chrome/browser/chromeos/login/wizard_controller.cc

Index: chrome/browser/chromeos/login/wizard_controller.cc
diff --git a/chrome/browser/chromeos/login/wizard_controller.cc b/chrome/browser/chromeos/login/wizard_controller.cc
index b69c59a70794463d916ae8231bc24db04089ccd7..6042585c99586f77dcfed04e36f372992e4012ed 100644
--- a/chrome/browser/chromeos/login/wizard_controller.cc
+++ b/chrome/browser/chromeos/login/wizard_controller.cc
@@ -620,7 +620,8 @@ void WizardController::RemoveObserver(Observer* observer) {
 }
 
 void WizardController::OnSessionStart() {
-  FOR_EACH_OBSERVER(Observer, observer_list_, OnSessionStart());
+  for (auto& observer : observer_list_)
+    observer.OnSessionStart();
 }
 
 void WizardController::SkipUpdateEnrollAfterEula() {
@@ -917,7 +918,8 @@ void WizardController::ShowCurrentScreen() {
 
   smooth_show_timer_.Stop();
 
-  FOR_EACH_OBSERVER(Observer, observer_list_, OnScreenChanged(current_screen_));
+  for (auto& observer : observer_list_)
+    observer.OnScreenChanged(current_screen_);
 
   current_screen_->Show();
 }