Add a new GetTlsUniqueChannelBinding method to SSLSocket, and implement nss version.

net/socket/ssl_client_socket_mac.h

Index: net/socket/ssl_client_socket_mac.h
diff --git a/net/socket/ssl_client_socket_mac.h b/net/socket/ssl_client_socket_mac.h
index d7ced4549ddca0b293efaf8345b5a5ceec8911cf..a3d91f85f44a56bbfa5957630cbd2cf659e181a2 100644
--- a/net/socket/ssl_client_socket_mac.h
+++ b/net/socket/ssl_client_socket_mac.h
@@ -42,14 +42,17 @@ class SSLClientSocketMac : public SSLClientSocket {
   // SSLClientSocket implementation.
   virtual void GetSSLCertRequestInfo(
       SSLCertRequestInfo* cert_request_info) OVERRIDE;
+  virtual NextProtoStatus GetNextProto(std::string* proto,
+                                       std::string* server_protos) OVERRIDE;
+  virtual ServerBoundCertService* GetServerBoundCertService() const OVERRIDE;
+
+  // SSLSocket implementation.
   virtual int ExportKeyingMaterial(const base::StringPiece& label,
                                    bool has_context,
                                    const base::StringPiece& context,
                                    unsigned char* out,
                                    unsigned int outlen) OVERRIDE;
-  virtual NextProtoStatus GetNextProto(std::string* proto,
-                                       std::string* server_protos) OVERRIDE;
-  virtual ServerBoundCertService* GetServerBoundCertService() const OVERRIDE;
+  virtual int GetTLSUniqueChannelBinding(std::string* out) OVERRIDE;
 
   // StreamSocket implementation.
   virtual int Connect(const CompletionCallback& callback) OVERRIDE;