mash: Replace int ShelfIDs with AppLaunchID strings.

ash/shelf/shelf_window_watcher_item_delegate.h

Index: ash/shelf/shelf_window_watcher_item_delegate.h
diff --git a/ash/shelf/shelf_window_watcher_item_delegate.h b/ash/shelf/shelf_window_watcher_item_delegate.h
index 7f82effd80f878734b6c193c870ac0b30fdfa2fd..c92148ca87a83ef7a244abd4f77a2abef6f9ce57 100644
--- a/ash/shelf/shelf_window_watcher_item_delegate.h
+++ b/ash/shelf/shelf_window_watcher_item_delegate.h
@@ -16,7 +16,7 @@ class WmWindow;
 // The Chrome OS settings window, task manager window, and panel windows.
 class ShelfWindowWatcherItemDelegate : public ShelfItemDelegate {
  public:
-  ShelfWindowWatcherItemDelegate(ShelfID id, WmWindow* window);
+  ShelfWindowWatcherItemDelegate(const ShelfID& id, WmWindow* window);
   ~ShelfWindowWatcherItemDelegate() override;
 
  private:
@@ -28,7 +28,6 @@ class ShelfWindowWatcherItemDelegate : public ShelfItemDelegate {
   void ExecuteCommand(uint32_t command_id, int32_t event_flags) override;
   void Close() override;
 
-  ShelfID id_;
   // The window associated with this item. Not owned.
   WmWindow* window_;