How to create a confirm message with a Gridview when AutogenerateDelete="true"

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="GridViewDelete.aspx.cs" Inherits="GridViewDelete" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
  <title>Untitled Page</title>
</head>
<body>
  <form id="form1" runat="server">
      <div>
          <asp:GridView ID="grdTest" runat="Server" AutoGenerateColumns="true" AutoGenerateDeleteButton="true"
              OnRowDataBound="grdTest_RowDataBound">
          </asp:GridView>
      </div>
  </form>
</body>
</html>
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Collections.Generic;

public partial class GridViewDelete : System.Web.UI.Page
{
   protected void Page_Load(object sender, EventArgs e)
   {

       //Check For postback
       if (!IsPostBack)
       {
           BindGrid();
       }


   }
   protected void BindGrid()
   {
      

       List<Customer> customers = new List<Customer>();

       Customer cust1 = new Customer(1, "Cust 1");
       Customer cust2 = new Customer(2, "Cust 2");
       Customer cust3 = new Customer(3, "Cust 3");

       customers.Add(cust1);
       customers.Add(cust2);
       customers.Add(cust3);

       grdTest.DataSource = customers;
       grdTest.DataBind();

   }
   protected void grdTest_RowDataBound(object sender, GridViewRowEventArgs e)
   {
       foreach (Control control in e.Row.Cells[0].Controls)
       {
           LinkButton DeleteButton = control as LinkButton;
           if (DeleteButton != null && DeleteButton.Text == "Delete")
           {
               DeleteButton.OnClientClick = "return(confirm('Are you sure you want to delete this record?'))";
           }
       }

   }
}


public class Customer
{
   public Customer(int id, string name)
   {
       ID = id;
       Name = name;
   }

   private int m_id;

   public int ID
   {
       get { return m_id; }
       set { m_id = value; }
   }

   private string m_name;

   public string Name
   {
       get { return m_name; }
       set { m_name = value; }
   }
}