Pepper: Add tests for the PPB_NetAddress_Private interface.

ppapi/cpp/private/net_address_private.cc

Index: ppapi/cpp/private/net_address_private.cc
diff --git a/ppapi/cpp/private/net_address_private.cc b/ppapi/cpp/private/net_address_private.cc
index fbae2b8d4a4c1bc3d0d301fcaa2093c0372fa59c..3b917959266d56ce68871d2556602527505ad734 100644
--- a/ppapi/cpp/private/net_address_private.cc
+++ b/ppapi/cpp/private/net_address_private.cc
@@ -21,6 +21,11 @@ template <> const char* interface_name<PPB_NetAddress_Private>() {
 }  // namespace
 
 // static
+bool NetAddressPrivate::IsAvailable() {
+  return has_interface<PPB_NetAddress_Private>();
+}
+
+// static
 bool NetAddressPrivate::AreEqual(const PP_NetAddress_Private& addr1,
                                  const PP_NetAddress_Private& addr2) {
   if (!has_interface<PPB_NetAddress_Private>())