Add a new GetNegotiatedProtocol method to StreamSocket and implement in all subclasses.

net/socket/ssl_server_socket_unittest.cc

Index: net/socket/ssl_server_socket_unittest.cc
diff --git a/net/socket/ssl_server_socket_unittest.cc b/net/socket/ssl_server_socket_unittest.cc
index ccb8ac1e92fbb3f52e2280ccd183280c65b23438..8de38b930d133e31704210c0cbbe4172c26db896 100644
--- a/net/socket/ssl_server_socket_unittest.cc
+++ b/net/socket/ssl_server_socket_unittest.cc
@@ -193,6 +193,10 @@ class FakeSocket : public StreamSocket {
     return base::TimeDelta::FromMicroseconds(-1);
   }
 
+  virtual NextProto GetNegotiatedProtocol() const {
+    return kProtoUnknown;
+  }
+
  private:
   net::BoundNetLog net_log_;
   FakeDataChannel* incoming_;