mash: Remove ShelfDelegate; move functions to ShelfModel.

ash/mus/shelf_delegate_mus.h

-// Copyright 2016 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_MUS_SHELF_DELEGATE_MUS_H_
-#define ASH_MUS_SHELF_DELEGATE_MUS_H_
-
-#include <string>
-
-#include "ash/public/cpp/shelf_types.h"
-#include "ash/shelf/shelf_delegate.h"
-#include "base/macros.h"
-
-namespace ash {
-
-// Manages communication between the mash shelf and the browser.
-class ShelfDelegateMus : public ShelfDelegate {
- public:
-  ShelfDelegateMus();
-  ~ShelfDelegateMus() override;
-
- private:
-  // ShelfDelegate:
-  ShelfID GetShelfIDForAppID(const std::string& app_id) override;
-  ShelfID GetShelfIDForAppIDAndLaunchID(const std::string& app_id,
-                                        const std::string& launch_id) override;
-  const std::string& GetAppIDForShelfID(ShelfID id) override;
-  void PinAppWithID(const std::string& app_id) override;
-  bool IsAppPinned(const std::string& app_id) override;
-  void UnpinAppWithID(const std::string& app_id) override;
-
-  DISALLOW_COPY_AND_ASSIGN(ShelfDelegateMus);
-};
-
-}  // namespace ash
-
-#endif  // ASH_MUS_SHELF_DELEGATE_MUS_H_