Update from https://crrev.com/305340

net/websockets/websocket_handshake_challenge.h

Index: net/websockets/websocket_handshake_challenge.h
diff --git a/net/websockets/websocket_handshake_challenge.h b/net/websockets/websocket_handshake_challenge.h
new file mode 100644
index 0000000000000000000000000000000000000000..e21f2b00f679bf6c52ef52123ff975718bfcda4c
--- /dev/null
+++ b/net/websockets/websocket_handshake_challenge.h
@@ -0,0 +1,21 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_WEBSOCKETS_WEBSOCKET_HANDSHAKE_CHALLENGE_H_
+#define NET_WEBSOCKETS_WEBSOCKET_HANDSHAKE_CHALLENGE_H_
+
+#include <string>
+
+#include "net/base/net_export.h"
+
+namespace net {
+
+// Given a WebSocket handshake challenge, compute the value that the server
+// should return in the Sec-WebSocket-Accept header.
+NET_EXPORT_PRIVATE std::string ComputeSecWebSocketAccept(
+    const std::string& key);
+
+}  // namespace net
+
+#endif  // NET_WEBSOCKETS_WEBSOCKET_HANDSHAKE_CHALLENGE_H_