mash: Fold ShelfItemDelegateManager into ShelfModel

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 209070d14b81de0613287d98508cee9083a9ca92..4a8dce815c429ebc5b31d057700799ed2fef3409 100644
--- a/ash/common/shelf/shelf_model_unittest.cc
+++ b/ash/common/shelf/shelf_model_unittest.cc
@@ -45,6 +45,8 @@ class TestShelfModelObserver : public ShelfModelObserver {
   void ShelfItemMoved(int start_index, int target_index) override {
     moved_count_++;
   }
+  void OnSetShelfItemDelegate(ShelfID id,
+                              ShelfItemDelegate* item_delegate) override {}
 
  private:
   void AddToResult(const std::string& format, int count, std::string* result) {
@@ -85,6 +87,7 @@ class ShelfModelTest : public testing::Test {
 
   void TearDown() override {
     observer_.reset();
+    model_->Shutdown();
     model_.reset();
   }