mash: Use mojo for ShelfItemDelegate and [app] MenuItem.

ash/common/shelf/shelf_model_unittest.cc

Index: ash/common/shelf/shelf_model_unittest.cc
diff --git a/ash/common/shelf/shelf_model_unittest.cc b/ash/common/shelf/shelf_model_unittest.cc
index 9589da1d73a467fcc5f969e84d03c7aa4307e5e1..e43451292679d2450f7b0dbd957f78d7b911885b 100644
--- a/ash/common/shelf/shelf_model_unittest.cc
+++ b/ash/common/shelf/shelf_model_unittest.cc
@@ -45,8 +45,9 @@ class TestShelfModelObserver : public ShelfModelObserver {
   void ShelfItemMoved(int start_index, int target_index) override {
     moved_count_++;
   }
-  void OnSetShelfItemDelegate(ShelfID id,
-                              ShelfItemDelegate* item_delegate) override {}
+  void OnSetShelfItemDelegate(
+      ShelfID id,
+      mojom::ShelfItemDelegate* item_delegate) override {}
 
  private:
   void AddToResult(const std::string& format, int count, std::string* result) {