Remove usage of FOR_EACH_OBSERVER macro in ash/

ash/wm/video_detector.cc

Index: ash/wm/video_detector.cc
diff --git a/ash/wm/video_detector.cc b/ash/wm/video_detector.cc
index 777f36f6cce9b59e8f48eda58447a9c9bb7aba2a..356bbd3d6a4b93e91c4c2d97ab6947d695c211bf 100644
--- a/ash/wm/video_detector.cc
+++ b/ash/wm/video_detector.cc
@@ -191,7 +191,8 @@ void VideoDetector::UpdateState() {
 
   if (state_ != new_state) {
     state_ = new_state;
-    FOR_EACH_OBSERVER(Observer, observers_, OnVideoStateChanged(state_));
+    for (auto& observer : observers_)
+      observer.OnVideoStateChanged(state_);
   }
 }