Special-case LocalDOMWindow for same-origin access in bindings.

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

 {% from 'utilities.cpp.tmpl' import declare_enum_validation_variable, v8_value_to_local_cpp_value %}
 
 {##############################################################################}
 {% macro generate_method(method, world_suffix) %}
 static void {{method.name}}{{method.overload_index}}Method{{world_suffix}}(const v8::FunctionCallbackInfo<v8::Value>& info) {
   {% filter format_remove_duplicates([
       'ExceptionState exceptionState',
       'ScriptState* scriptState = ']) %}
   {% set define_exception_state -%}
   ExceptionState exceptionState(info.GetIsolate(), ExceptionState::ExecutionContext, "{{interface_name}}", "{{method.name}}");
@@ skipping 11 matching lines @@
 
   {% if not method.is_static %}
   {% if method.returns_promise %}
   // V8DOMConfiguration::DoNotCheckHolder
   // Make sure that info.Holder() really points to an instance of the type.
   if (!{{v8_class}}::hasInstance(info.Holder(), info.GetIsolate())) {
     {{throw_type_error(method, '"Illegal invocation"')}}
     return;
   }
   {% endif %}
+  {% if interface_name == 'Window' and not method.is_cross_origin %}
+  // Same-origin methods are never exposed via the cross-origin interceptors.
+  // Since same-origin access requires a LocalDOMWindow, it is safe to downcast
+  // here.
+  LocalDOMWindow* impl = toLocalDOMWindow({{v8_class}}::toImpl(info.Holder()));
+  {% else %}
   {{cpp_class}}* impl = {{v8_class}}::toImpl(info.Holder());
   {% endif %}
+  {% endif %}
 
   {# Security checks #}
   {% if method.is_check_security_for_receiver %}
   {{define_exception_state}}
   {% if interface_name == 'EventTarget' %}
   // Performance hack for EventTarget.  Checking whether it's a Window or not
   // prior to the call to BindingSecurity::shouldAllowAccessTo increases 30%
   // of speed performance on Android Nexus 7 as of Dec 2015.  ALWAYS_INLINE
   // didn't work in this case.
   if (const DOMWindow* window = impl->toDOMWindow()) {
@@ skipping 595 matching lines @@
                           if method.overloads else
                           method.runtime_enabled_feature_name) %}
 const V8DOMConfiguration::MethodConfiguration {{method.name}}MethodConfiguration = {{method_configuration(method)}};
 V8DOMConfiguration::installMethod(isolate, world, v8::Local<v8::Object>(), prototypeObject, interfaceObject, signature, {{method.name}}MethodConfiguration);
 {% endfilter %}{# runtime_enabled() #}
 {% endfilter %}{# exposed() #}
 {% endfilter %}{# secure_context() #}
 {% endfor %}
 {% endif %}
 {%- endmacro %}