TrashAsset.cs

#if UNITY_EDITOR
using UnityEditor;
using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class TrashAsset : MonoBehaviour
{
	public string originalAssetPath;
	public string trashAssetPath;
	private int count;

	void OnValidate ()
	{
		if (count++ == 0) {
			// Redo
			UndoExtention.MoveAssetToTrash (this);
		}
	}
}
#endif

UndoExtention.cs

using System;
using System.Collections.Generic;
using System.IO;
using UnityEditor;
using UnityEngine;
using Object = UnityEngine.Object;

public class Example
{
	[MenuItem ("Assets/Move to Trash")]
	static void Delete ()
	{
		Object[] os = Selection.objects;

		if (os.Length == 0)
			return;

		UndoExtention.MoveToTrash (os);
	}
}

[InitializeOnLoad]
public class UndoExtention
{
	public static TrashAsset[] trashAssets;

	static UndoExtention ()
	{
		trashAssets = Resources.FindObjectsOfTypeAll<TrashAsset> ();
		Undo.undoRedoPerformed += () => {

			foreach (var trashAsset in trashAssets) {

				if (!trashAsset) {
					//Undo
					File.Move (trashAsset.trashAssetPath, trashAsset.originalAssetPath);
					File.Move (AssetDatabase.GetTextMetaDataPathFromAssetPath (trashAsset.trashAssetPath), AssetDatabase.GetTextMetaDataPathFromAssetPath (trashAsset.originalAssetPath));
					AssetDatabase.ImportAsset (trashAsset.originalAssetPath);
					ArrayUtility.Remove (ref trashAssets, trashAsset);
				}
			}
		};
	}

	public static void MoveToTrash (Object obj, string name = "Move to Trash")
	{
		MoveToTrash (new Object[]{ obj }, name);
	}

	public static void MoveToTrash (Object[] objs, string name = "Move to Trash")
	{
		GameObject g = EditorUtility.CreateGameObjectWithHideFlags ("Trash", HideFlags.HideAndDontSave);
		GameObject.DontDestroyOnLoad (g);
		foreach (var o in objs) {
			Internal_MoveAssetToTrash (o, g, null);
		}
		Undo.RegisterCreatedObjectUndo (g, name);
	}

	public static void MoveAssetToTrash (TrashAsset trashAsset)
	{
		Internal_MoveAssetToTrash (null, null, trashAsset);
	}

	public static void Internal_MoveAssetToTrash (Object o, GameObject g, TrashAsset trashAsset)
	{
		string assetPath =	"";
		bool isObj = o;
		if (o) {
			assetPath =	AssetDatabase.GetAssetPath (o);
		} else if (trashAsset != null) {
			assetPath = trashAsset.originalAssetPath;

		}

		string newName = string.Format ("{0}{1}", Path.GetFileNameWithoutExtension (assetPath), DateTime.Now.ToString ("HH-m-s"));
		string error = AssetDatabase.RenameAsset (assetPath, newName);

		if (string.IsNullOrEmpty (error)) {
			string newAssetPath = Path.Combine (Path.GetDirectoryName (assetPath), newName + Path.GetExtension (assetPath));
			AssetDatabase.MoveAssetToTrash (newAssetPath);

			if (isObj) {
				trashAsset = g.AddComponent<TrashAsset> ();
				trashAsset.originalAssetPath = assetPath;
			}

#if UNITY_EDITOR_OSX
			trashAsset.trashAssetPath = string.Format ("/Users/{0}/.Trash/{1}{2}", Environment.UserName, newName, Path.GetExtension (assetPath));
#elif !UNITY_EDITOR_OSX
						throw new NotImplementedException ();
						trashAsset.trashAssetPath = string.Format("{0}\\{1}{2}",Directory.GetDirectories("C:\\$Recycle.Bin")[0],newName, Path.GetExtension (assetPath));
#endif
			if (!ArrayUtility.Contains<TrashAsset> (trashAssets, trashAsset))
				ArrayUtility.Add (ref trashAssets, trashAsset);
		} else {
			Debug.LogError (error);
		}
	}
}