SO_REUSEPORT is moved from AddressReuse feature to Broadcast feature.

net/udp/udp_socket_libevent.cc

 // 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.
 
 #include "net/udp/udp_socket_libevent.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <netdb.h>
 #include <sys/socket.h>
@@ skipping 447 matching lines @@
   return result;
 }
 
 int UDPSocketLibevent::SetSocketOptions() {
   int true_value = 1;
   if (socket_options_ & SOCKET_OPTION_REUSE_ADDRESS) {
     int rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEADDR, &true_value,
                         sizeof(true_value));
     if (rv < 0)
       return MapSystemError(errno);
-#if defined(SO_REUSEPORT)
+  }
+  if (socket_options_ & SOCKET_OPTION_BROADCAST) {
+    int rv;
+#if defined(OS_MACOSX)
+    // SO_REUSEPORT on OSX permits multiple processes to each receive
+    // UDP multicast or broadcast datagrams destined for the bound
+    // port.
     rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEPORT, &true_value,
                     sizeof(true_value));
     if (rv < 0)
       return MapSystemError(errno);
-#endif
-  }
-  if (socket_options_ & SOCKET_OPTION_BROADCAST) {
-    int rv = setsockopt(socket_, SOL_SOCKET, SO_BROADCAST, &true_value,
-                        sizeof(true_value));
+#endif  // defined(OS_MACOSX)
+    rv = setsockopt(socket_, SOL_SOCKET, SO_BROADCAST, &true_value,
+                    sizeof(true_value));
     if (rv < 0)
       return MapSystemError(errno);
   }
   return OK;
 }
 
 int UDPSocketLibevent::DoBind(const IPEndPoint& address) {
   SockaddrStorage storage;
   if (!address.ToSockAddr(storage.addr, &storage.addr_len))
     return ERR_UNEXPECTED;
   int rv = bind(socket_, storage.addr, storage.addr_len);
   return rv < 0 ? MapSystemError(errno) : rv;
 }
 
 int UDPSocketLibevent::RandomBind(const IPEndPoint& address) {
   DCHECK(bind_type_ == DatagramSocket::RANDOM_BIND && !rand_int_cb_.is_null());
 
   // Construct IPAddressNumber of appropriate size (IPv4 or IPv6) of 0s.
   IPAddressNumber ip(address.address().size());
 
   for (int i = 0; i < kBindRetries; ++i) {
     int rv = DoBind(IPEndPoint(ip, rand_int_cb_.Run(kPortStart, kPortEnd)));
     if (rv == OK || rv != ERR_ADDRESS_IN_USE)
       return rv;
   }
   return DoBind(IPEndPoint(ip, 0));
 }
 
 }  // namespace net