Array and map members for unions.

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

 {%- set class_name = union.name ~ "_Data" -%}
 {%- set enum_name = union.name ~ "_Tag" -%}
 {%- import "struct_macros.tmpl" as struct_macros %}
 
 class {{class_name}} {
  public:
   // Used to identify Mojom Union Data Classes.
   typedef void MojomUnionDataType;
   static {{class_name}}* New(mojo::internal::Buffer* buf);
   {{class_name}}();
@@ skipping 14 matching lines @@
 {%  for field in union.fields %}
     {{field.name|upper}},
 {%- endfor %}
   };
 
   // A note on layout:
   // "Each non-static data member is allocated as if it were the sole member of
   // a struct." - Section 9.5.2 ISO/IEC 14882:2011 (The C++ Spec)
   union MOJO_ALIGNAS(8) Union_ {
 {%- for field in union.fields %}
-{%-   if field.kind|is_string_kind or field.kind|is_struct_kind %}
+{%-   if field.kind|is_object_kind %}
     uint64_t f_{{field.name}};
 {%-   elif field.kind.spec == 'b' %}
     uint8_t f_{{field.name}} : 1;
 {%-   elif field.kind|is_enum_kind %}
     int32_t f_{{field.name}};
 {%-   else %}
     {{field.kind|cpp_pod_type}} f_{{field.name}};
 {%-   endif %}
 {%- endfor %}
     uint64_t unknown;
   };
 
   uint32_t size;
   {{enum_name}} tag;
   Union_ data;
 
   void EncodePointersAndHandles(std::vector<mojo::Handle>* handles);
   void DecodePointersAndHandles(std::vector<mojo::Handle>* handles);
 };
 static_assert(sizeof({{class_name}}) == 16,
               "Bad sizeof({{class_name}})");
 static_assert(sizeof({{class_name}}::Union_) == 8,
               "Bad sizeof({{class_name}}::Union_)");