Worklet: Introduce "pending tasks struct" concept defined in the Worklet spec

third_party/WebKit/Source/core/workers/WorkletObjectProxy.h

-// Copyright 2017 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 WorkletObjectProxy_h
-#define WorkletObjectProxy_h
-
-#include "core/CoreExport.h"
-#include "platform/heap/GarbageCollected.h"
-#include "platform/weborigin/KURL.h"
-#include "platform/wtf/text/WTFString.h"
-
-namespace blink {
-
-// A proxy to talk to the Worklet object on the main thread from the worklet
-// global scope that may exist in the main thread or on a different thread.
-class CORE_EXPORT WorkletObjectProxy : public GarbageCollectedMixin {
- public:
-  // Called when the worklet module script is fetched and evaluated. |success|
-  // is true if the sequence is completed without an error.
-  virtual void DidFetchAndInvokeScript(int32_t request_id, bool success) = 0;
-};
-
-}  // namespace blink
-
-#endif  // WorkletObjectProxy_h