FIX: Replace StandaloneInputModule button not dirtying scene (#999).

Author: Rene Damm

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -87,6 +87,10 @@ This release includes a number of Quality-of-Life improvements for a range of co
 - Removing a device no longer has the potential of corrupting state change monitors (and thus actions getting triggered) from other devices.
   * This bug led to input being missed on a device once another device had been removed.
 
+#### Actions
+
+- Clicking the "Replace with InputSystemUIInputModule" button in the inspector when looking at `StandaloneInputModule`, the resulting operation is now undoable and will properly dirty the scene.
+
 ## [1.0.0-preview.3] - 2019-11-14
 
 ### Fixed

Packages/com.unity.inputsystem/InputSystem/Plugins/UI/StandaloneInputModuleEditor.cs

@@ -36,8 +36,9 @@ public override void OnInspectorGUI()
                     EditorGUILayout.HelpBox("You are using StandaloneInputModule, which uses the old InputManager. You also have the new InputSystem enabled in your project. Click the button below to replace this component with a InputSystemUIInputModule, which uses the new InputSystem (recommended).", MessageType.Info);
                 if (GUILayout.Button("Replace with InputSystemUIInputModule"))
                 {
-                    ((StandaloneInputModule)target).gameObject.AddComponent<InputSystemUIInputModule>();
-                    DestroyImmediate(target);
+                    var go = ((StandaloneInputModule)target).gameObject;
+                    Undo.DestroyObjectImmediate(target);
+                    Undo.AddComponent<InputSystemUIInputModule>(go);
                     return;
                 }
                 GUILayout.Space(10);