Add LayoutTests for the fixed multithread GC bug of ServiceWorker Navigation Preload

third_party/WebKit/Source/core/testing/WorkerInternals.h

 // Copyright 2016 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.
 
 #ifndef WorkerInternals_h
 #define WorkerInternals_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/GarbageCollected.h"
 
 namespace blink {
 
 class OriginTrialsTest;
 class ScriptState;
 
 class WorkerInternals final : public GarbageCollectedFinalized<WorkerInternals>,
                               public ScriptWrappable {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   static WorkerInternals* create() { return new WorkerInternals(); }
   virtual ~WorkerInternals();
 
   OriginTrialsTest* originTrialsTest() const;
   void countFeature(ScriptState*, uint32_t feature);
   void countDeprecation(ScriptState*, uint32_t feature);
 
+  void collectGarbage(ScriptState*);
+
   DEFINE_INLINE_TRACE() {}
 
  private:
   explicit WorkerInternals();
 };
 
 }  // namespace blink
 
 #endif  // WorkerInternals_h