Extended implementation to use interface as arguments

third_party/WebKit/Source/core/timing/PerformanceObserver.idl

 // Copyright 2015 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.
 
 // http://w3c.github.io/performance-timeline/#idl-def-PerformanceObserverCallback
 callback PerformanceObserverCallback = void (PerformanceObserverEntryList entries, PerformanceObserver observer);
+[ExperimentalCallbackFunction] callback PerformanceObserverInnerCallback = void (PerformanceObserverEntryList entries, PerformanceObserver observer);
 
 // http://w3c.github.io/performance-timeline/#the-performance-observer-interface
 [
     CustomConstructor(PerformanceObserverCallback callback),
     RuntimeEnabled=PerformanceObserver,
 ] interface PerformanceObserver {
     [RaisesException] void observe(PerformanceObserverInit options);
     void disconnect();
 };