mash: Replace int ShelfIDs with AppLaunchID strings.

ash/shell/window_watcher_shelf_item_delegate.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_SHELL_WINDOW_WATCHER_SHELF_ITEM_DELEGATE_H_
 #define ASH_SHELL_WINDOW_WATCHER_SHELF_ITEM_DELEGATE_H_
 
 #include "ash/public/cpp/shelf_item.h"
 #include "ash/public/cpp/shelf_item_delegate.h"
 #include "base/compiler_specific.h"
@@ skipping 12 matching lines @@
 
   // ShelfItemDelegate:
   void ItemSelected(std::unique_ptr<ui::Event> event,
                     int64_t display_id,
                     ShelfLaunchSource source,
                     const ItemSelectedCallback& callback) override;
   void ExecuteCommand(uint32_t command_id, int32_t event_flags) override;
   void Close() override;
 
  private:
-  ShelfID id_;
   WindowWatcher* watcher_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowWatcherShelfItemDelegate);
 };
 
 }  // namespace shell
 }  // namespace ash
 
 #endif  // ASH_SHELL_WINDOW_WATCHER_SHELF_ITEM_DELEGATE_H_