mash: Remove ShelfDelegate; move functions to ShelfModel.

ash/test/test_shell_delegate.h

Index: ash/test/test_shell_delegate.h
diff --git a/ash/test/test_shell_delegate.h b/ash/test/test_shell_delegate.h
index ab64ef4e9f62f79b1f2b402918695bb902857d0c..9110cda806fce3f3b0dc6f3e30e02f91184ce8ca 100644
--- a/ash/test/test_shell_delegate.h
+++ b/ash/test/test_shell_delegate.h
@@ -41,8 +41,9 @@ class TestShellDelegate : public ShellDelegate {
   void PreShutdown() override;
   void Exit() override;
   keyboard::KeyboardUI* CreateKeyboardUI() override;
+  void ShelfInit() override;
+  void ShelfShutdown() override;
   void OpenUrlFromArc(const GURL& url) override;
-  ShelfDelegate* CreateShelfDelegate(ShelfModel* model) override;
   SystemTrayDelegate* CreateSystemTrayDelegate() override;
   std::unique_ptr<WallpaperDelegate> CreateWallpaperDelegate() override;
   TestSessionStateDelegate* CreateSessionStateDelegate() override;