ash: Move ShelfWidget ownership to WmShelf and refactor access to it

ash/common/shelf/shelf_widget.h

 // Copyright (c) 2012 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.
 
 #ifndef ASH_COMMON_SHELF_SHELF_WIDGET_H_
 #define ASH_COMMON_SHELF_SHELF_WIDGET_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 16 matching lines @@
 class ShelfView;
 class StatusAreaWidget;
 class WmShelf;
 class WmWindow;
 
 class ASH_EXPORT ShelfWidget : public views::Widget,
                                public views::WidgetObserver,
                                public ShelfBackgroundAnimatorObserver,
                                public ShelfLayoutManagerObserver {
  public:
-  ShelfWidget(WmWindow* shelf_container,
-              WmWindow* status_container,
-              WmShelf* wm_shelf);
+  ShelfWidget(WmWindow* shelf_container, WmShelf* wm_shelf);
   ~ShelfWidget() override;
 
+  void CreateStatusAreaWidget(WmWindow* status_container);
+
   // Returns if shelf alignment option is enabled, and the user is able to
   // adjust the alignment (guest and supervised mode users cannot for example).
   static bool ShelfAlignmentAllowed();
 
   void OnShelfAlignmentChanged();
 
   // DEPRECATED: Prefer WmShelf::GetAlignment().
   ShelfAlignment GetAlignment() const;
 
   // Sets the shelf's background type.
@@ skipping 71 matching lines @@
   void WillDeleteShelfLayoutManager() override;
 
  private:
   class DelegateView;
   friend class DelegateView;
 
   WmShelf* wm_shelf_;
 
   // Owned by the shelf container's window.
   ShelfLayoutManager* shelf_layout_manager_;
+
+  // Owned by the native widget.
   StatusAreaWidget* status_area_widget_;
 
   // |delegate_view_| is the contents view of this widget and is cleaned up
   // during CloseChildWindows of the associated RootWindowController.
   DelegateView* delegate_view_;
   // View containing the shelf items. Owned by the views hierarchy.
   ShelfView* shelf_view_;
   ShelfBackgroundAnimator background_animator_;
   bool activating_as_fallback_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfWidget);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELF_SHELF_WIDGET_H_