Remove usage of FOR_EACH_OBSERVER macro in ash/common

ash/common/wm/dock/docked_window_layout_manager.cc

Index: ash/common/wm/dock/docked_window_layout_manager.cc
diff --git a/ash/common/wm/dock/docked_window_layout_manager.cc b/ash/common/wm/dock/docked_window_layout_manager.cc
index 180817620afd18b30a44a13473c503bbb7600327..f25f09df3f6c82423edba4e8e5adf1d60a3ef921 100644
--- a/ash/common/wm/dock/docked_window_layout_manager.cc
+++ b/ash/common/wm/dock/docked_window_layout_manager.cc
@@ -1297,8 +1297,8 @@ void DockedWindowLayoutManager::UpdateDockBounds(
       dock_container_->GetBounds().y(), dock_inset, work_area.height());
   docked_bounds_ =
       bounds + dock_container_->GetBoundsInScreen().OffsetFromOrigin();
-  FOR_EACH_OBSERVER(DockedWindowLayoutManagerObserver, observer_list_,
-                    OnDockBoundsChanging(bounds, reason));
+  for (auto& observer : observer_list_)
+    observer.OnDockBoundsChanging(bounds, reason);
   // Show or hide background for docked area.
   gfx::Rect background_bounds(docked_bounds_);
   if (shelf_observer_)