Mojo C++ bindings: share DataView class between chromium and blink variants.

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

-{%- set mojom_type = union|get_qualified_name_for_kind %}
-
-// static
-bool UnionTraits<{{mojom_type}}::DataView, {{mojom_type}}Ptr>::Read(
-    {{mojom_type}}::DataView input,
-    {{mojom_type}}Ptr* output) {
-  *output = {{mojom_type}}::New();
-  {{mojom_type}}Ptr& result = *output;
-
-  internal::UnionAccessor<{{mojom_type}}> result_acc(result.get());
-  switch (input.tag()) {
-{%- for field in union.fields %}
-    case {{mojom_type}}::Tag::{{field.name|upper}}: {
-{%-   set name = field.name %}
-{%-   set kind = field.kind %}
-{%-   set serializer_type = kind|unmapped_type_for_serializer %}
-{%-   if kind|is_object_kind %}
-      result_acc.SwitchActive({{mojom_type}}::Tag::{{name|upper}});
-      if (!input.Read{{name|under_to_camel}}(result_acc.data()->{{name}}))
-        return false;
-
-{%-   elif kind|is_any_handle_or_interface_kind %}
-      auto result_{{name}} = input.Take{{name|under_to_camel}}();
-      result->set_{{name}}(std::move(result_{{name}}));
-
-{%-   elif kind|is_enum_kind %}
-      decltype(result->get_{{name}}()) result_{{name}};
-      if (!input.Read{{name|under_to_camel}}(&result_{{name}}))
-        return false;
-      result->set_{{name}}(result_{{name}});
-
-{%-   else %}
-      result->set_{{name}}(input.{{name}}());
-{%-   endif %}
-      break;
-    }
-{%- endfor %}
-    default:
-      return false;
-  }
-  return true;
-}