Use the current context as the creation context for cross-origin objects.

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

 {% filter format_blink_cpp_source_code %}
 
 {% include 'copyright_block.txt' %}
 #include "{{v8_class_or_partial}}.h"
 
 {% for filename in cpp_includes if filename != '%s.h' % cpp_class_or_partial %}
 #include "{{filename}}"
 {% endfor %}
 
 namespace blink {
@@ skipping 180 matching lines @@
 {% if has_access_check_callbacks and not is_partial %}
 {{exported}}bool securityCheck(v8::Local<v8::Context> accessingContext, v8::Local<v8::Object> accessedObject, v8::Local<v8::Value> data) {
   {% if interface_name == 'Window' %}
   v8::Isolate* isolate = v8::Isolate::GetCurrent();
   v8::Local<v8::Object> window = V8Window::findInstanceInPrototypeChain(accessedObject, isolate);
   if (window.IsEmpty())
     return false;  // the frame is gone.
 
   const DOMWindow* targetWindow = V8Window::toImpl(window);
   return BindingSecurity::shouldAllowAccessTo(toLocalDOMWindow(toDOMWindow(accessingContext)), targetWindow, BindingSecurity::ErrorReportOption::DoNotReport);
-  {% else %}{# if interface_name == 'Window' #}
-  {# Not 'Window' means it\'s Location. #}
+  {% elif interface_name == 'Location' %}
   {{cpp_class}}* impl = {{v8_class}}::toImpl(accessedObject);
   return BindingSecurity::shouldAllowAccessTo(toLocalDOMWindow(toDOMWindow(accessingContext)), impl, BindingSecurity::ErrorReportOption::DoNotReport);
-  {% endif %}{# if interface_name == 'Window' #}
+  {% else %}
+  static_assert(false, "Unexpected security check for interface {{interface_name}}");

[Yuki, 2017/01/26 10:41:54]

nit: #error "message" does the trick and it's more light-weight.

[dcheng, 2017/01/27 01:31:42]

Done.

+  {% endif %}
 }
 
 {% if has_cross_origin_named_enumerator %}
 static const struct {
   using GetterCallback = void(*)(const v8::PropertyCallbackInfo<v8::Value>&);
   using SetterCallback = void(*)(v8::Local<v8::Value>, const V8CrossOriginSetterInfo&);
 
   const char* const name;
   const GetterCallback getter;
   const SetterCallback setter;
 } kCrossOriginAttributeTable[] = {
   {##### Cross-origin attributes #####}
   {% for attribute in attributes if attribute.has_cross_origin_getter or attribute.has_cross_origin_setter %}
   {
     "{{attribute.name}}",
-    {%+ if attribute.has_cross_origin_getter %}&{{cpp_class}}V8Internal::{{attribute.name}}AttributeGetter{% else %}nullptr{% endif %},
+    {% if attribute.has_cross_origin_getter %}
+    {% if attribute.has_custom_getter %}
+    {{v8_class}}::{{attribute.name}}AttributeGetterCustom,
+    {% else %}
+    &{{cpp_class}}V8Internal::{{attribute.name}}AttributeGetter,
+    {% endif %}
+    {% else %}
+    nullptr,
+    {% endif %}
     {%+ if attribute.has_cross_origin_setter %}&{{cpp_class}}V8Internal::{{attribute.name}}AttributeSetter{% else %}nullptr{% endif %},
   },
   {% endfor %}
   {##### Cross-origin methods #####}
   {% for method in methods if method.is_cross_origin %}
   {"{{method.name}}", &{{cpp_class}}V8Internal::{{method.name}}OriginSafeMethodGetter, nullptr},
   {% endfor %}
 };
 {% endif %}
 
@@ skipping 46 matching lines @@
       {{v8_class}}::toImpl(info.Holder())->frame());
 }
 {% endif %}
 
 {% if has_cross_origin_named_enumerator %}
 {{exported}}void crossOriginNamedEnumerator(const v8::PropertyCallbackInfo<v8::Array>& info) {
   Vector<String> names;
   for (const auto& attribute : kCrossOriginAttributeTable)
     names.push_back(attribute.name);
 
-  v8SetReturnValue(
-      info,
-      ToV8(names, info.Holder(), info.GetIsolate()).As<v8::Array>());
+  // Use the current context as the creation context, as a cross-origin access
+  // may involve an object that does not have a creation context.
+  v8SetReturnValue(info,
+                   ToV8(names, info.GetIsolate()->GetCurrentContext()->Global(),
+                        info.GetIsolate()).As<v8::Array>());
 }
 {% endif %}
 
 {% if has_cross_origin_indexed_getter %}
 {{exported}}void crossOriginIndexedGetter(uint32_t index, const v8::PropertyCallbackInfo<v8::Value>& info) {
   {% if indexed_property_getter.is_custom %}
   {{v8_class}}::indexedPropertyGetterCustom(index, info);
   {% else %}
   {{cpp_class}}V8Internal::indexedPropertyGetter(index, info);
   {% endif %}
@@ skipping 353 matching lines @@
 {% block has_instance %}{% endblock %}
 {% block to_impl %}{% endblock %}
 {% block to_impl_with_type_check %}{% endblock %}
 {##############################################################################}
 {% block prepare_prototype_and_interface_object %}{% endblock %}
 {##############################################################################}
 {% block partial_interface %}{% endblock %}
 }  // namespace blink
 
 {% endfilter %}{# format_blink_cpp_source_code #}