[Bindings] Replace V8HiddenValue in generated code with V8PrivateProperty

third_party/WebKit/Source/bindings/templates/interface.cpp.tmpl

 {% extends 'interface_base.cpp.tmpl' %}
 
 {##############################################################################}
 {% block indexed_property_getter %}
 {% if indexed_property_getter and not indexed_property_getter.is_custom %}
 {% set getter = indexed_property_getter %}
 static void indexedPropertyGetter(uint32_t index, const v8::PropertyCallbackInfo<v8::Value>& info) {
   {% if getter.is_raises_exception %}
   ExceptionState exceptionState(info.GetIsolate(), ExceptionState::IndexedGetterContext, "{{interface_name}}");
   {% endif %}
@@ skipping 473 matching lines @@
    properly supports the incumbent realm. #}
 {% block origin_safe_method_setter %}
 {% if has_origin_safe_method_setter %}
 static void {{cpp_class}}OriginSafeMethodSetter(v8::Local<v8::Name> name, v8::Local<v8::Value> v8Value, const v8::PropertyCallbackInfo<void>& info) {
   if (!name->IsString())
     return;
   v8::Local<v8::Object> holder = {{v8_class}}::findInstanceInPrototypeChain(info.Holder(), info.GetIsolate());
   if (holder.IsEmpty())
     return;
   {{cpp_class}}* impl = {{v8_class}}::toImpl(holder);
   v8::String::Utf8Value attributeName(name);

[Yuki, 2017/03/31 13:38:29]

I'm uneasy with this name...  This is a setter callback for a method.  |name| is
a method name.

[peria, 2017/04/03 04:58:43]

Done.

   ExceptionState exceptionState(info.GetIsolate(), ExceptionState::SetterContext, "{{interface_name}}", *attributeName);
   if (!BindingSecurity::shouldAllowAccessTo(currentDOMWindow(info.GetIsolate()), impl, exceptionState)) {
     return;
   }
 
   {# The findInstanceInPrototypeChain() call above only returns a non-empty handle if info.Holder() is an Object. #}
-  V8HiddenValue::setHiddenValue(ScriptState::current(info.GetIsolate()), v8::Local<v8::Object>::Cast(info.Holder()), name.As<v8::String>(), v8Value);
+  V8PrivateProperty::createSymbol(info.GetIsolate(), *attributeName)

[Yuki, 2017/03/31 13:38:29]

Could you add a comment that attributeName must match with {{method.name}} in
FooOriginSafeMethodGetter in methods.cpp.tmpl?  (Actually opposite. 
{{method.name}} must match with |name|.

By the way, we already have |name| of type v8::String.
name => attributeName => v8String again
looks a little silly.  But this is not a critical path, so I'm okay with this.

[peria, 2017/04/03 04:58:43]

Done.

+      .set(v8::Local<v8::Object>::Cast(info.Holder()), v8Value);
 }
 {% endif %}
 {% endblock %}
 
 {% block origin_safe_method_setter_callback %}
 {% if has_origin_safe_method_setter %}
 void {{v8_class_or_partial}}::{{cpp_class}}OriginSafeMethodSetterCallback(v8::Local<v8::Name> name, v8::Local<v8::Value> v8Value, const v8::PropertyCallbackInfo<void>& info) {
   {{cpp_class}}V8Internal::{{cpp_class}}OriginSafeMethodSetter(name, v8Value, info);
 }
 {% endif %}
@@ skipping 411 matching lines @@
 }
 
 {% for method in methods if method.overloads and method.overloads.has_partial_overloads %}
 void {{v8_class}}::register{{method.name | blink_capitalize}}MethodForPartialInterface(void (*method)(const v8::FunctionCallbackInfo<v8::Value>&)) {
   {{cpp_class}}V8Internal::{{method.name}}MethodForPartialInterface = method;
 }
 
 {% endfor %}
 {% endif %}
 {% endblock %}