Editor script for repeating a texture over an object

I wanna conver the following script to Editor script.
This script can change the tile size based on the scale.

Code (CSharp):

1.  
2. void Start(){
3.     Vector2 SS = renderer.material.mainTextureScale;
4.     SS.x = transform.localScale.x;
5.     SS.y = transform.localScale.y;
6.     renderer.material.mainTextureScale = SS;
7. }

I've tried this, however it doesn't work.

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using UnityEditor;
4.  
5. public class MaterialAutoRepeatInspector : MaterialEditor {
6.  
7.     public override void OnInspectorGUI() {
8.         base.OnInspectorGUI ();
9.         if (!isVisible)    return;
10.  
11.         Material targetMat = target as Material;
12.         Vector2 texScale = targetMat.mainTextureScale;
13.         Transform targetTrans = target as Transform;
14.         texScale.x =  targetTrans.localScale.x;
15.         texScale.y =  targetTrans.localScale.y;
16.         targetMat.mainTextureScale = texScale;
17.     }
18. }
19.  

Any suggestion?