mash: Serialize ShelfIDs for property conversion and transport.

ash/shelf/shelf_model.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_SHELF_MODEL_H_
 #define ASH_SHELF_SHELF_MODEL_H_
 
 #include <map>
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "ash/public/cpp/shelf_item.h"
 #include "ash/public/interfaces/shelf.mojom.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 
 namespace ash {
 
 class ShelfItemDelegate;
 class ShelfModelObserver;
 
 // Model used for shelf items. Owns ShelfItemDelegates but does not create them.
-// TODO(msw): Remove id conversion functions; check for item presence as needed.
 class ASH_EXPORT ShelfModel {
  public:
   ShelfModel();
   ~ShelfModel();
 
   // Pins an app with |app_id| to shelf. A running instance will get pinned.
   // In case there is no running instance a new shelf item is created and
   // pinned.
   void PinAppWithID(const std::string& app_id);
 
@@ skipping 67 matching lines @@
 
   std::map<ShelfID, std::unique_ptr<ShelfItemDelegate>>
       id_to_item_delegate_map_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfModel);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELF_SHELF_MODEL_H_