ash: Reorder shutdown of ShelfLayoutManager and StatusAreaWidget

ash/shelf/shelf_widget.h

Index: ash/shelf/shelf_widget.h
diff --git a/ash/shelf/shelf_widget.h b/ash/shelf/shelf_widget.h
index 2a63c8d240cee749840932ace3e8ca60a72a0d12..967f53f4610f755779877c528514f88467e420a6 100644
--- a/ash/shelf/shelf_widget.h
+++ b/ash/shelf/shelf_widget.h
@@ -75,8 +75,8 @@ class ASH_EXPORT ShelfWidget : public views::Widget,
 
   aura::Window* window_container() { return window_container_; }
 
-  // TODO(harrym): Remove when Status Area Widget is a child view.
-  void ShutdownStatusAreaWidget();
+  // Clean up prior to deletion.
+  void Shutdown();
 
   // Force the shelf to be presented in an undimmed state.
   void ForceUndimming(bool force);