Reduce usage of FOR_EACH_OBSERVER macro in base

base/process/port_provider_mac.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/process/port_provider_mac.h"
 
 namespace base {
 
 PortProvider::PortProvider() : lock_(), observer_list_() {}
 PortProvider::~PortProvider() {}
 
 void PortProvider::AddObserver(Observer* observer) {
   base::AutoLock l(lock_);
   observer_list_.AddObserver(observer);
 }
 
 void PortProvider::RemoveObserver(Observer* observer) {
   base::AutoLock l(lock_);
   observer_list_.RemoveObserver(observer);
 }
 
 void PortProvider::NotifyObservers(ProcessHandle process) {
   base::AutoLock l(lock_);
-  FOR_EACH_OBSERVER(Observer, observer_list_, OnReceivedTaskPort(process));
+  for (auto& observer : observer_list_)
+    observer.OnReceivedTaskPort(process);
 }
 
 }  // namespace base