Mojo: Add warning of invalid serialization results (in debug build).

mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_definition.tmpl

Index: mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_definition.tmpl
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_definition.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_definition.tmpl
index f48cca72fb45734058cf6eda9554dc674c2d671a..f81bbb44e8c51d260824eb19804939e3c31790e2 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_definition.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_definition.tmpl
@@ -15,11 +15,30 @@ void Serialize_({{struct.name}}Ptr input, mojo::internal::Buffer* buf,
         internal::{{struct.name}}_Data::New(buf);
 {%- for pf in struct.packed.packed_fields %}
 {%-   if pf.field.kind|is_object_kind %}
+{%-     if pf.field.kind|is_any_array_kind %}
+    mojo::SerializeArray_<{{pf.field.kind|get_array_validate_params|indent(26)}}>(
+        mojo::internal::Forward(input->{{pf.field.name}}), buf, &result->{{pf.field.name}}.ptr);
+{%-     else %}
     Serialize_(mojo::internal::Forward(input->{{pf.field.name}}), buf, &result->{{pf.field.name}}.ptr);
-{%-   elif pf.field.kind|is_interface_kind %}
-    result->{{pf.field.name}} = input->{{pf.field.name}}.PassMessagePipe().release();
+{%-     endif %}
+{%-     if not pf.field.kind|is_nullable_kind %}
+    MOJO_INTERNAL_DLOG_SERIALIZATION_WARNING(
+        mojo::internal::IsNonNullableValidationEnabled() &&
+            !result->{{pf.field.name}}.ptr,
+        mojo::internal::VALIDATION_ERROR_UNEXPECTED_NULL_POINTER);
+{%-     endif %}
 {%-   elif pf.field.kind|is_any_handle_kind %}
+{%-     if pf.field.kind|is_interface_kind %}
+    result->{{pf.field.name}} = input->{{pf.field.name}}.PassMessagePipe().release();
+{%-     else %}
     result->{{pf.field.name}} = input->{{pf.field.name}}.release();
+{%-     endif %}
+{%-     if not pf.field.kind|is_nullable_kind %}
+    MOJO_INTERNAL_DLOG_SERIALIZATION_WARNING(
+        mojo::internal::IsNonNullableValidationEnabled() &&
+            !result->{{pf.field.name}}.is_valid(),
+        mojo::internal::VALIDATION_ERROR_UNEXPECTED_INVALID_HANDLE);
+{%-     endif %}
 {%-   else %}
     result->{{pf.field.name}} = input->{{pf.field.name}};
 {%-   endif %}