[mojo] Add pickling support for native-only structs

mojo/public/tools/bindings/generators/cpp_templates/module-internal.h.tmpl

 // Copyright 2013 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.
 
 {%- if variant -%}
 {%-   set variant_path = "%s-%s"|format(module.path, variant) -%}
 {%- else -%}
 {%-   set variant_path = module.path -%}
 {%- endif -%}
 
 {%- set header_guard = "%s_INTERNAL_H_"|
         format(variant_path|upper|
                   replace("/","_")|replace(".","_")|replace("-", "_")) %}
 
 #ifndef {{header_guard}}
 #define {{header_guard}}
 
 #include "mojo/public/cpp/bindings/lib/bindings_internal.h"
 #include "mojo/public/cpp/bindings/lib/buffer.h"
+#include "mojo/public/cpp/bindings/lib/native_serialization.h"
 #include "mojo/public/cpp/bindings/lib/union_accessor.h"
 #include "mojo/public/cpp/bindings/lib/value_traits.h"
 #include "mojo/public/cpp/bindings/struct_ptr.h"
+{%- for header in extra_headers %}
+#include "{{header}}"
+{%- endfor %}
 
 {%- for import in imports %}
 #include "{{import.module.path}}-internal.h"
 {%- endfor %}
 
 namespace mojo {
 namespace internal {
 class BoundsChecker;
 }
 }
@@ skipping 43 matching lines @@
 
 }  // namespace internal
 {%- if variant %}
 }  // namespace {{variant}}
 {%- endif %}
 {%- for namespace in namespaces_as_array|reverse %}
 }  // namespace {{namespace}}
 {%- endfor %}
 
 #endif  // {{header_guard}}