Pull up singleton behaviour.

Assets/Cryville/Crtr/UI/PopupManager.cs

@@ -1,23 +1,11 @@
-using System;
+using Cryville.Common.Unity;
 using UnityEngine;
-using UnityEngine.UI;
 
 namespace Cryville.Crtr.UI {
-	public class PopupManager : MonoBehaviour {
-		static PopupManager s_instance;
-		public static PopupManager Instance { get { return s_instance; } }
-
+	public class PopupManager : SingletonBehaviour<PopupManager> {
 		[SerializeField]
 		GameObject m_popupPrefab;
 
-		void Awake() {
-			if (s_instance != null) {
-				Destroy(gameObject);
-				throw new InvalidOperationException("Attempted to initialize a singleton twice.");
-			}
-			s_instance = this;
-		}
-
 		public void Create(string msg) {
 			Instantiate(m_popupPrefab, transform, false).GetComponent<Popup>().Message = msg;
 		}