mash: Replace int ShelfIDs with AppLaunchID strings.

ash/public/cpp/shelf_item.h

 // Copyright 2017 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_PUBLIC_CPP_SHELF_ITEM_H_
 #define ASH_PUBLIC_CPP_SHELF_ITEM_H_
 
 #include <vector>
 
-#include "ash/public/cpp/app_launch_id.h"
 #include "ash/public/cpp/ash_public_export.h"
 #include "ash/public/cpp/shelf_types.h"
 #include "base/strings/string16.h"
 #include "ui/gfx/image/image_skia.h"
 
 namespace ash {
 
 struct ASH_PUBLIC_EXPORT ShelfItem {
   ShelfItem();
   ShelfItem(const ShelfItem& shelf_item);
   ~ShelfItem();
 
   ShelfItemType type = TYPE_UNDEFINED;
 
   // Image to display in the shelf.
   gfx::ImageSkia image;
 
-  // Assigned by the model when the item is added.
-  ShelfID id = kInvalidShelfID;
-
   // Running status.
   ShelfItemStatus status = STATUS_CLOSED;
 
   // The application id and launch id for this shelf item.
-  AppLaunchId app_launch_id;
+  ShelfID id;
 
   // The title to display for tooltips, etc.
   base::string16 title;
 
   // Whether the tooltip should be shown on hover; generally true.
   bool shows_tooltip = true;
 
   // Whether the item is pinned by a policy preference (ie. user cannot un-pin).
   bool pinned_by_policy = false;
 };
 
 typedef std::vector<ShelfItem> ShelfItems;
 
 }  // namespace ash
 
 #endif  // ASH_PUBLIC_CPP_SHELF_ITEM_H_