Allow server sockets to rebind to same port if there is nothing actively listening on that port.

net/socket/tcp_server_socket_win.cc

Index: net/socket/tcp_server_socket_win.cc
diff --git a/net/socket/tcp_server_socket_win.cc b/net/socket/tcp_server_socket_win.cc
index eb15ffbdaf9bb691a57642e77e4b9fa46a357f86..817e73a4aa3972f14d00644a97dc1e2e14c09171 100644
--- a/net/socket/tcp_server_socket_win.cc
+++ b/net/socket/tcp_server_socket_win.cc
@@ -21,6 +21,7 @@ TCPServerSocketWin::TCPServerSocketWin(net::NetLog* net_log,
     : socket_(INVALID_SOCKET),
       socket_event_(WSA_INVALID_EVENT),
       accept_socket_(NULL),
+      reuse_address_(false),
       net_log_(BoundNetLog::Make(net_log, NetLog::SOURCE_SOCKET)) {
   net_log_.BeginEvent(NetLog::TYPE_SOCKET_ALIVE,
                       source.ToEventParametersCallback());
@@ -32,6 +33,14 @@ TCPServerSocketWin::~TCPServerSocketWin() {
   net_log_.EndEvent(NetLog::TYPE_SOCKET_ALIVE);
 }
 
+void TCPServerSocketWin::AllowAddressReuse() {
+  DCHECK(CalledOnValidThread());
+  DCHECK_EQ(socket_, INVALID_SOCKET);
+  DCHECK_EQ(socket_event_, WSA_INVALID_EVENT);
+
+  reuse_address_ = true;
+}
+
 int TCPServerSocketWin::Listen(const IPEndPoint& address, int backlog) {
   DCHECK(CalledOnValidThread());
   DCHECK_GT(backlog, 0);
@@ -56,11 +65,15 @@ int TCPServerSocketWin::Listen(const IPEndPoint& address, int backlog) {
     return result;
   }
 
+  int result = SetSocketOptions();
+  if (result != OK)
+    return result;
+
   SockaddrStorage storage;
   if (!address.ToSockAddr(storage.addr, &storage.addr_len))
     return ERR_INVALID_ARGUMENT;
 
-  int result = bind(socket_, storage.addr, storage.addr_len);
+  result = bind(socket_, storage.addr, storage.addr_len);
   if (result < 0) {
     PLOG(ERROR) << "bind() returned an error";
     result = MapSystemError(WSAGetLastError());
@@ -115,6 +128,18 @@ int TCPServerSocketWin::Accept(
   return result;
 }
 
+int TCPServerSocketWin::SetSocketOptions() {
+  BOOL true_value = 1;
+  if (reuse_address_) {
+    int rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEADDR,
+                        reinterpret_cast<const char*>(&true_value),
+                        sizeof(true_value));
+    if (rv < 0)
+      return MapSystemError(errno);
+  }
+  return OK;
+}
+
 int TCPServerSocketWin::AcceptInternal(scoped_ptr<StreamSocket>* socket) {
   SockaddrStorage storage;
   int new_socket = accept(socket_, storage.addr, &storage.addr_len);