Clean up NPN/ALPN-related SSLClientSocket bits.

net/socket/ssl_client_socket_nss.h

 // Copyright (c) 2012 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_SOCKET_SSL_CLIENT_SOCKET_NSS_H_
 #define NET_SOCKET_SSL_CLIENT_SOCKET_NSS_H_
 
 #include <certt.h>
 #include <keyt.h>
 #include <nspr.h>
@@ skipping 51 matching lines @@
   // runner should be supplied instead.
   SSLClientSocketNSS(base::SequencedTaskRunner* nss_task_runner,
                      scoped_ptr<ClientSocketHandle> transport_socket,
                      const HostPortPair& host_and_port,
                      const SSLConfig& ssl_config,
                      const SSLClientSocketContext& context);
   ~SSLClientSocketNSS() override;
 
   // SSLClientSocket implementation.
   void GetSSLCertRequestInfo(SSLCertRequestInfo* cert_request_info) override;
-  NextProtoStatus GetNextProto(std::string* proto) override;
+  NextProtoStatus GetNextProto(std::string* proto) const override;
 
   // SSLSocket implementation.
   int ExportKeyingMaterial(const base::StringPiece& label,
                            bool has_context,
                            const base::StringPiece& context,
                            unsigned char* out,
                            unsigned int outlen) override;
   int GetTLSUniqueChannelBinding(std::string* out) override;
 
   // StreamSocket implementation.
@@ skipping 126 matching lines @@
   // Added the following code Debugging in release mode.
   mutable base::Lock lock_;
   // This is mutable so that CalledOnValidThread can set it.
   // It's guarded by |lock_|.
   mutable base::PlatformThreadId valid_thread_id_;
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_SSL_CLIENT_SOCKET_NSS_H_