mojo::Serialize*_() calls now propogate/return validation errors.

mojo/public/cpp/bindings/lib/map_serialization_forward.h

 // Copyright 2015 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.
 
 // Headers such as array_serialization.h can include this file to avoid circular
 // dependencies on map_serialization.h.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_MAP_SERIALIZATION_FORWARD_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_MAP_SERIALIZATION_FORWARD_H_
 
 namespace mojo {
 namespace internal {
 
 class ArrayValidateParams;
 class Buffer;
 
 template <typename Key, typename Value>
 class Map_Data;
 
 }  // namespace internal
 
 template <typename Key, typename Value>
 class Map;
 
 template <typename MapKey,
           typename MapValue,
           typename DataKey,
           typename DataValue>
-void SerializeMap_(Map<MapKey, MapValue>* input,
-                   internal::Buffer* buf,
-                   internal::Map_Data<DataKey, DataValue>** output,
-                   const internal::ArrayValidateParams* value_validate_params);
+internal::ValidationError SerializeMap_(
+    Map<MapKey, MapValue>* input,
+    internal::Buffer* buf,
+    internal::Map_Data<DataKey, DataValue>** output,
+    const internal::ArrayValidateParams* value_validate_params);
 template <typename MapKey, typename MapValue>
 size_t GetSerializedSize_(const Map<MapKey, MapValue>& input);
 
 template <typename MapKey,
           typename MapValue,
           typename DataKey,
           typename DataValue>
 void Deserialize_(internal::Map_Data<DataKey, DataValue>* input,
                   Map<MapKey, MapValue>* output);
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_MAP_SERIALIZATION_FORWARD_H_