Move third_party/mojo/src/mojo/public to mojo/public

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 34 matching lines @@
   {{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_)");