Fix V8 bindings for named constructors to set prototype object correctly

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

Index: third_party/WebKit/Source/bindings/templates/interface.cpp.tmpl
diff --git a/third_party/WebKit/Source/bindings/templates/interface.cpp.tmpl b/third_party/WebKit/Source/bindings/templates/interface.cpp.tmpl
index a7e7b2ecbddb5cbcc66f4c711f6351ebb845ecc9..dba9c7332a07dd5c1510611a39fa224bd5cc7740 100644
--- a/third_party/WebKit/Source/bindings/templates/interface.cpp.tmpl
+++ b/third_party/WebKit/Source/bindings/templates/interface.cpp.tmpl
@@ -522,6 +522,8 @@ static void {{cpp_class}}OriginSafeMethodSetter(v8::Local<v8::Name> name, v8::Lo
 {% block named_constructor %}
 {% from 'methods.cpp.tmpl' import generate_constructor with context %}
 {% if named_constructor %}
+{% set parent_wrapper_type_info = '&V8%s::wrapperTypeInfo' % parent_interface
+                                  if parent_interface else '0' %}
 {% set active_scriptwrappable_inheritance =
     'InheritFromActiveScriptWrappable'
     if active_scriptwrappable else
@@ -532,7 +534,7 @@ static void {{cpp_class}}OriginSafeMethodSetter(v8::Local<v8::Name> name, v8::Lo
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wglobal-constructors"
 #endif
-const WrapperTypeInfo {{v8_class}}Constructor::wrapperTypeInfo = { gin::kEmbedderBlink, {{v8_class}}Constructor::domTemplate, {{v8_class}}::trace, {{v8_class}}::traceWrappers, 0, {{prepare_prototype_and_interface_object_func}}, "{{interface_name}}", 0, WrapperTypeInfo::WrapperTypeObjectPrototype, WrapperTypeInfo::{{wrapper_class_id}}, WrapperTypeInfo::{{active_scriptwrappable_inheritance}}, WrapperTypeInfo::{{event_target_inheritance}}, WrapperTypeInfo::{{lifetime}} };
+const WrapperTypeInfo {{v8_class}}Constructor::wrapperTypeInfo = { gin::kEmbedderBlink, {{v8_class}}Constructor::domTemplate, {{v8_class}}::trace, {{v8_class}}::traceWrappers, 0, {{prepare_prototype_and_interface_object_func}}, "{{interface_name}}", {{parent_wrapper_type_info}}, WrapperTypeInfo::WrapperTypeObjectPrototype, WrapperTypeInfo::{{wrapper_class_id}}, WrapperTypeInfo::{{active_scriptwrappable_inheritance}}, WrapperTypeInfo::{{event_target_inheritance}}, WrapperTypeInfo::{{lifetime}} };
 #if defined(COMPONENT_BUILD) && defined(WIN32) && COMPILER(CLANG)
 #pragma clang diagnostic pop
 #endif
@@ -548,12 +550,47 @@ v8::Local<v8::FunctionTemplate> {{v8_class}}Constructor::domTemplate(v8::Isolate
   result = v8::FunctionTemplate::New(isolate, {{v8_class}}ConstructorCallback);
   v8::Local<v8::ObjectTemplate> instanceTemplate = result->InstanceTemplate();
   instanceTemplate->SetInternalFieldCount({{v8_class}}::internalFieldCount);
-  result->SetClassName(v8AtomicString(isolate, "{{cpp_class}}"));
+  result->SetClassName(v8AtomicString(isolate, "{{named_constructor.name}}"));
   result->Inherit({{v8_class}}::domTemplate(isolate, world));
   data->setInterfaceTemplate(world, &domTemplateKey, result);
   return result;
 }
 
+void {{v8_class}}Constructor::NamedConstructorAttributeGetter(
+    v8::Local<v8::Name> propertyName,
+    const v8::PropertyCallbackInfo<v8::Value>& info) {
+  v8::Local<v8::Context> currentContext = info.Holder()->CreationContext();

[haraken, 2017/01/25 03:37:16]

currentContext => creationContext

[sashab, 2017/01/25 04:54:15]

Done.

+  V8PerContextData* perContextData = V8PerContextData::from(currentContext);
+  if (!perContextData)

[haraken, 2017/01/25 03:37:16]

// TODO(yukishiino): Return a valid named constructor even after the context is
detached

[sashab, 2017/01/25 04:54:15]

Done :)

+    return;
+
+  v8::Local<v8::Function> namedConstructor = perContextData->constructorForType(&{{v8_class}}Constructor::wrapperTypeInfo);
+
+  // Set the prototype of named constructors to the regular constructor.
+  auto privateProperty = V8PrivateProperty::getNamedConstructorInitialized(info.GetIsolate());
+  v8::Local<v8::Value> privateValue = privateProperty.get(currentContext, namedConstructor);
+  if (privateValue.IsEmpty()) {
+    v8::Local<v8::Function> interface = perContextData->constructorForType(&{{v8_class}}::wrapperTypeInfo);
+    // Only Window exposes named constructors, so that will always be the interface name.
+    ExceptionState exceptionState(info.GetIsolate(), ExceptionState::GetterContext, "Window", "{{named_constructor.name}}");
+    v8::MaybeLocal<v8::Value> interfacePrototype = interface->Get(currentContext, v8AtomicString(info.GetIsolate(), "prototype"));

[haraken, 2017/01/25 03:37:16]

We want to avoid using MaybeLocal. Also this Get should not fail.

  v8::Local<v8::Value> interfacePrototype =
interface->Get(...).ToLocalChecked();

[sashab, 2017/01/25 04:54:15]

Sorry, did this locally but didn't upload it :/ Done.

+    if (interfacePrototype.IsEmpty()) {
+      exceptionState.throwTypeError("Could not get prototype for {{v8_class}}.");
+      return;
+    }
+
+    v8::Maybe<bool> setResult = namedConstructor->Set(currentContext, v8AtomicString(info.GetIsolate(), "prototype"), interfacePrototype.ToLocalChecked());

[haraken, 2017/01/25 03:37:16]

Ditto. Avoid using MaybeLocal. Also this Set should not fail.

bool result = namedConstructor->Set(...).ToChecked();

[sashab, 2017/01/25 04:54:15]

Done. Also removed exceptionContext and just returned if it fails. Is this
better?

+    if (setResult.IsNothing() || setResult.ToChecked() != true) {
+      exceptionState.throwTypeError("Could not set prototype for {{named_constructor.name}}.");
+      return;
+    }
+
+    privateProperty.set(currentContext, namedConstructor, v8::True(info.GetIsolate()));
+  }
+
+  v8SetReturnValue(info, namedConstructor);
+}
+
 {% endif %}
 {% endblock %}