Bind: Use VariadicTemplates in bind_internal.h

base/bind_unittest.nc

Index: base/bind_unittest.nc
diff --git a/base/bind_unittest.nc b/base/bind_unittest.nc
index 33b5f5c858e6b29b8861faf8951c866bbdc3c31f..259638673a91af7022151228bbbe5f70d4e3fcd7 100644
--- a/base/bind_unittest.nc
+++ b/base/bind_unittest.nc
@@ -190,7 +190,7 @@ void WontCompile() {
   weak_ptr_with_non_void_return_type.Run();
 }
 
-#elif defined(NCTEST_DISALLOW_ASSIGN_DIFFERENT_TYPES)  // [r"fatal error: no viable conversion from 'Callback<typename internal::BindState<typename internal::FunctorTraits<void \(\*\)\(int\)>::RunnableType, typename internal::FunctorTraits<void \(\*\)\(int\)>::RunType, void \(\)>::UnboundRunType>' to 'Callback<void \(\)>'"]
+#elif defined(NCTEST_DISALLOW_ASSIGN_DIFFERENT_TYPES)  // [r"fatal error: no viable conversion from 'Callback<typename internal::BindState<typename internal::FunctorTraits<void \(\*\)\(int\)>::RunnableType, typename internal::FunctorTraits<void \(\*\)\(int\)>::RunType, internal::TypeList<> >::UnboundRunType>' to 'Callback<void \(\)>'"]
 
 // Bind result cannot be assigned to Callbacks with a mismatching type.
 void WontCompile() {