AllowBroadcast() is exposed to NaCl.

ppapi/cpp/private/udp_socket_private.h

Index: ppapi/cpp/private/udp_socket_private.h
diff --git a/ppapi/cpp/private/udp_socket_private.h b/ppapi/cpp/private/udp_socket_private.h
index 5179e721e9afb54f7055f5be1cc7a34513dfe7e6..66fef8f35702be3197daf29d9206b6c22b7b0b1a 100644
--- a/ppapi/cpp/private/udp_socket_private.h
+++ b/ppapi/cpp/private/udp_socket_private.h
@@ -8,6 +8,7 @@
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/c/private/ppb_udp_socket_private.h"
 #include "ppapi/cpp/resource.h"
+#include "ppapi/cpp/var.h"
 
 namespace pp {
 
@@ -21,6 +22,7 @@ class UDPSocketPrivate : public Resource {
   // Returns true if the required interface is available.
   static bool IsAvailable();
 
+  int32_t SetSocketFeature(PP_UDPSocketFeature_Private name, const Var& value);
   int32_t Bind(const PP_NetAddress_Private* addr,
                const CompletionCallback& callback);
   bool GetBoundAddress(PP_NetAddress_Private* addr);