IDL: Generate union type containers

Source/bindings/templates/union.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file has been auto-generated by {{code_generator}}. DO NOT MODIFY!
 
 #ifndef {{macro_guard}}
 #define {{macro_guard}}
 
+{% for filename in header_includes %}
+#include "{{filename}}"
+{% endfor %}
+
 namespace blink {
 
+{% for decl in header_forward_decls %}
+class {{decl}};
+{% endfor %}
+
 {% for container in containers %}
 class {{container.cpp_class}} final {
-    // FIXME: Implement
+    ALLOW_ONLY_INLINE_ALLOCATION();
+public:
+    {{container.cpp_class}}();
+    bool isNull() const { return m_type == SpecificTypeNone; }
+
+    {% for member in container.members %}
+    bool is{{member.type_name}}() const { return m_type == {{member.specific_type_enum}}; }
+    {{member.rvalue_cpp_type}} getAs{{member.type_name}}();
+    void set{{member.type_name}}({{member.rvalue_cpp_type}});
+
+    {% endfor %}
+private:
+    enum SpecificTypes {
+        SpecificTypeNone,
+        {% for member in container.members %}
+        {{member.specific_type_enum}},
+        {% endfor %}
+    };
+    SpecificTypes m_type;
+
+    {% for member in container.members %}
+    {{member.cpp_type}} m_{{member.cpp_name}};
+    {% endfor %}
 };
 
+class V8{{container.cpp_class}} final {
+public:
+    static void toImpl(v8::Isolate*, v8::Handle<v8::Value>, {{container.cpp_class}}&, ExceptionState&);
+};
+
+v8::Handle<v8::Value> toV8({{container.cpp_class}}&, v8::Handle<v8::Object>, v8::Isolate*);
+
+template <class CallbackInfo>
+inline void v8SetReturnValue(const CallbackInfo& callbackInfo, {{container.cpp_class}}& impl)
+{
+    v8SetReturnValue(callbackInfo, toV8(impl, callbackInfo.Holder(), callbackInfo.GetIsolate()));
+}
+
 {% endfor %}
 } // namespace blink
 
 #endif // {{macro_guard}}