Mojo: Report bindings validation errors via MojoNotifyBadMessage

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

 {%- import "validation_macros.tmpl" as validation_macros %}
 {%- set class_name = union.name ~ "_Data" %}
 {%- set enum_name = union.name ~ "_Tag" -%}
 
 // static
 {{class_name}}* {{class_name}}::New(mojo::internal::Buffer* buf) {
   return new (buf->Allocate(sizeof({{class_name}}))) {{class_name}}();
 }
 
 // static
-bool {{class_name}}::Validate(const void* data,
-                              mojo::internal::BoundsChecker* bounds_checker,
-                              bool inlined) {
+bool {{class_name}}::Validate(
+    const void* data,
+    mojo::internal::ValidationContext* validation_context,
+    bool inlined) {
   if (!data)
     return true;
 
-  if (!ValidateUnionHeaderAndClaimMemory(data, inlined, bounds_checker))
+  if (!ValidateUnionHeaderAndClaimMemory(data, inlined, validation_context))
     return false;
 
   const {{class_name}}* object = static_cast<const {{class_name}}*>(data);
   ALLOW_UNUSED_LOCAL(object);
 
   switch (object->tag) {
 {%  for field in union.fields %}
     case {{enum_name}}::{{field.name|upper}}: {
 {%-   set field_expr = "object->data.f_" ~ field.name %}
 {{validation_macros.validate_field(field, field_expr, union.name, false)|indent(4)}}
       return true;
     }
 {%- endfor %}
     default: {
       ReportValidationError(
+          validation_context,
           mojo::internal::VALIDATION_ERROR_UNKNOWN_UNION_TAG,
           "unknown tag in {{union.name}}");
       return false;
     }
   }
 }
 
 void {{class_name}}::set_null() {
   size = 0U;
   tag = static_cast<{{enum_name}}>(0);
@@ skipping 21 matching lines @@
 {%- for field in union.fields %}
     case {{enum_name}}::{{field.name|upper}}: {
 {%-   if field.kind|is_object_kind %}
       mojo::internal::Decode(&data.f_{{field.name}});
 {%-   endif %}
       return;
     }
 {%- endfor %}
   }
 }