Move speedUpFrameRate and coolDownFrameRate into Window.

Runtime/editor/editor_window.cs

             if (regenerateLayerTree) {
                 this._regenerateLayerTree = true;
             }
-            UIWidgetsGlobalSettings.instance.speedUpFrameRate();
-            UIWidgetsGlobalSettings.instance.coolDownFrameRate();
+            doSpeedUp();
+            doCoolDown();
         }
 
         public override void render(Scene scene) {

Runtime/ui/window.cs

 using System.Collections.Generic;
 using Unity.UIWidgets.async;
 using Unity.UIWidgets.foundation;
+using UnityEngine;
 
 namespace Unity.UIWidgets.ui {
     public delegate void VoidCallback();
 
         public float getFPS() {
             return 1.0f / this.fpsDeltaTime;
+        }
+        
+        public static Action speedUpFrameRate;
+        public static Action coolDownFrameRate;
+        
+        static Timer scheduleFrameTimer;
+        public const int defaultMaxTargetFrameRate = 60;
+        public const int defaultMinTargetFrameRate = 15;
+        
+        public static void doSpeedUp() {
+            if (speedUpFrameRate == null) {
+                Application.targetFrameRate = defaultMaxTargetFrameRate;
+            }
+            else {
+                speedUpFrameRate();
+            }
+        }
+
+        public static void doCoolDown() {
+            if (coolDownFrameRate == null) {
+                scheduleFrameTimer?.cancel();
+                scheduleFrameTimer = instance.run(
+                    new TimeSpan(0, 0, 0, 0, 200),
+                    () => {
+                        Application.targetFrameRate = defaultMinTargetFrameRate;
+                        scheduleFrameTimer = null;
+                    });
+            }
+            else {
+                coolDownFrameRate();
+            }
         }
     }
 }

Runtime/engine/global_settings.cs

-using System;
-using Unity.UIWidgets.async;
-using Unity.UIWidgets.ui;
-using UnityEngine;
-
-namespace Unity.UIWidgets.engine {
-    public class UIWidgetsGlobalSettings {
-        UIWidgetsGlobalSettings() {
-            this.speedUpFrameRate = () => { this.defaultSpeedUp(); };
-            this.coolDownFrameRate = () => { this.defaultCoolDown(); };
-        }
-
-        public Action speedUpFrameRate;
-        public Action coolDownFrameRate;
-
-        public static UIWidgetsGlobalSettings instance {
-            get { return _instance; }
-        }
-        
-        static UIWidgetsGlobalSettings _instance = new UIWidgetsGlobalSettings();
-        
-        Timer scheduleFrameTimer;
-        public const int defaultMaxTargetFrameRate = 60;
-        public const int defaultMinTargetFrameRate = 15;
-        
-        void defaultSpeedUp() {
-            Application.targetFrameRate = defaultMaxTargetFrameRate;
-        }
-
-        void defaultCoolDown() {
-            this.scheduleFrameTimer?.cancel();
-            this.scheduleFrameTimer = Window.instance.run(
-                new TimeSpan(0, 0, 0, 0, 200),
-                () => {
-                    Application.targetFrameRate = defaultMinTargetFrameRate;
-                    this.scheduleFrameTimer = null;
-                });
-        }
-    }
-}

Runtime/engine/global_settings.cs.meta

-fileFormatVersion: 2
-guid: 3ffd4ed5bc5c4758b56f365a50418fff
-timeCreated: 1554884592