Reduce FOR_EACH_OBSERVER usage in ui/

ui/base/user_activity/user_activity_detector.cc

 // Copyright 2014 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 "ui/base/user_activity/user_activity_detector.h"
 
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "build/build_config.h"
@@ skipping 105 matching lines @@
 
 void UserActivityDetector::HandleActivity(const ui::Event* event) {
   base::TimeTicks now = GetCurrentTime();
   last_activity_time_ = now;
   last_activity_name_ = event->name();
   if (last_observer_notification_time_.is_null() ||
       (now - last_observer_notification_time_).InMillisecondsF() >=
       kNotifyIntervalMs) {
     if (VLOG_IS_ON(1))
       VLOG(1) << "Reporting user activity: " << GetEventDebugString(event);
-    FOR_EACH_OBSERVER(UserActivityObserver, observers_, OnUserActivity(event));
+    for (UserActivityObserver& observer : observers_)
+      observer.OnUserActivity(event);
     last_observer_notification_time_ = now;
   }
 }
 
 }  // namespace ui