public int width;
public int height;

public string seed;
public bool useRandomSeed;

[Range(0, 100)]
public int randomFillPercent;

int [,] map;

void Start()
{
    GenerateMap();
}

void GenerateMap()
{
    map = new int[width,height];
    RandomFillMap();
}

void RandomFillMap()
{
    if(useRandomSeed)
    {
        seed = Time.time.ToString();
    }

    System.Random psuedoRandom = new System.Random(seed.GetHashCode());

    for(int x = 0; x < width; x++)
    {
        for(int y = 0; y < height; y++)
        {
            map[x,y] = (psuedoRandom.Next(0, 100) < randomFillPercent) ? 1 : 0;
        }
    }
}

void OnDrawGizmos()
{
    if(map != null)
    {
        //.. Draw Grid (but we never get here, because map == null)
    }
}