Cleanup ash shelf accessor functions.

ash/shelf/overflow_button.h

 // Copyright 2013 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_SHELF_OVERFLOW_BUTTON_H_
 #define ASH_SHELF_OVERFLOW_BUTTON_H_
 
 #include "ash/shelf/shelf_types.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/views/controls/button/custom_button.h"
 
 namespace ash {
 
-class ShelfLayoutManager;
+class Shelf;
 
 // Shelf overflow chevron button.
 class OverflowButton : public views::CustomButton {
  public:
-  OverflowButton(views::ButtonListener* listener, ShelfLayoutManager* shelf);
+  OverflowButton(views::ButtonListener* listener, Shelf* shelf);
   ~OverflowButton() override;
 
   void OnShelfAlignmentChanged();
 
  private:
   void PaintBackground(gfx::Canvas* canvas, int alpha);
 
   // views::View overrides:
   void OnPaint(gfx::Canvas* canvas) override;
 
   // Left and right images are rotations of bottom_image and are
   // owned by the overflow button.
   gfx::ImageSkia left_image_;
   gfx::ImageSkia right_image_;
   // Bottom image is owned by the resource bundle.
   const gfx::ImageSkia* bottom_image_;
-  ShelfLayoutManager* shelf_;
+  Shelf* shelf_;
 
   DISALLOW_COPY_AND_ASSIGN(OverflowButton);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELF_OVERFLOW_BUTTON_H_