Adds a method to TCPServerSocket to adopt a socket.

net/socket/tcp_server_socket.h

 // Copyright (c) 2011 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_TCP_SERVER_SOCKET_H_
 #define NET_SOCKET_TCP_SERVER_SOCKET_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "net/base/ip_endpoint.h"
 #include "net/base/net_export.h"
 #include "net/socket/server_socket.h"
+#include "net/socket/socket_descriptor.h"
 #include "net/socket/tcp_socket.h"
 
 namespace net {
 
 class NetLog;
 struct NetLogSource;
 
 // A server socket that uses TCP as the transport layer.
 class NET_EXPORT TCPServerSocket : public ServerSocket {
  public:
   TCPServerSocket(NetLog* net_log, const NetLogSource& source);
   ~TCPServerSocket() override;
 
+  // Takes ownership of |socket|, which has been opened, but may or may not be
+  // bound or listening. The caller must determine this based on the provenance
+  // of the socket and act accordingly.
+  int AdoptUnconnectedSocket(SocketDescriptor socket);

[mmenke, 2017/04/21 19:20:38]

This works for connected sockets, too, right?  Maybe just AdoptSocket?

[Raul Vera, 2017/05/01 05:35:25]

It doesn't work for connected sockets, as the peer address will not get set
properly. The idea is that the server code will subsequently call Accept, which
will set the peer address.

However, in the case of a server only an unconnected socket makes sense so it
doesn't matter much. I've changed the name to what you suggest and added a
comment that it should not be connected.

+
   // net::ServerSocket implementation.
   int Listen(const IPEndPoint& address, int backlog) override;
   int GetLocalAddress(IPEndPoint* address) const override;
   int Accept(std::unique_ptr<StreamSocket>* socket,
              const CompletionCallback& callback) override;
 
   // Detachs from the current thread, to allow the socket to be transferred to
   // a new thread. Should only be called when the object is no longer used by
   // the old thread.
   void DetachFromThread();
@@ skipping 16 matching lines @@
   std::unique_ptr<TCPSocket> accepted_socket_;
   IPEndPoint accepted_address_;
   bool pending_accept_;
 
   DISALLOW_COPY_AND_ASSIGN(TCPServerSocket);
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_TCP_SERVER_SOCKET_H_