Pepper: Add support for multicast in PPB_UDPSocket API

ppapi/shared_impl/private/net_address_private_impl.h

Index: ppapi/shared_impl/private/net_address_private_impl.h
diff --git a/ppapi/shared_impl/private/net_address_private_impl.h b/ppapi/shared_impl/private/net_address_private_impl.h
index d71263546f39a365a61d49df730ed9a35e706e24..814633b4dff41f9e8bdfeca4aaa59d3a4af7b826 100644
--- a/ppapi/shared_impl/private/net_address_private_impl.h
+++ b/ppapi/shared_impl/private/net_address_private_impl.h
@@ -37,6 +37,8 @@ class PPAPI_SHARED_EXPORT NetAddressPrivateImpl {
   static std::string DescribeNetAddress(const PP_NetAddress_Private& addr,
                                         bool include_port);
 
+  static void GetAnyAddress(PP_Bool is_ipv6, PP_NetAddress_Private* addr);
+
   // Conversion methods to make PPB_NetAddress resource work with
   // PP_NetAddress_Private.
   // TODO(yzshen): Remove them once PPB_NetAddress resource doesn't use