How to load binary from MemoryStream into WebBrowser in .Net C#

string fileName = @"C:\Users\test1.pdf";
byte[] buff = null;
FileStream fs = new FileStream(fileName,              
             FileMode.Open,FileAccess.Read);
BinaryReader br = new BinaryReader(fs);
long numBytes = new FileInfo(fileName).Length;
buff = br.ReadBytes((int) numBytes);
MemoryStream stream = new MemoryStream(buff);
webBrowser1.DocumentStream = stream;
webBrowser1.Show();