概要

using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine;
using UnityEngine.SceneManagement;

[InitializeOnLoad]
public static class Example
{
    static Example()
    {
        EditorSceneManager.sceneDirtied += OnSceneDirtied;
    }

    private static void OnSceneDirtied( Scene scene )
    {
        Debug.Log( scene.name );
    }
}

シーンの dirty フラグが立った時に
EditorSceneManager.sceneDirtied が呼び出されます