Revert of Pass per-frame task runners to Workers (when possible)

third_party/WebKit/Source/core/workers/ParentFrameTaskRunners.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 ParentFrameTaskRunners_h
-#define ParentFrameTaskRunners_h
-
-#include "core/CoreExport.h"
-#include "wtf/Allocator.h"
-#include "wtf/Noncopyable.h"
-#include "wtf/PtrUtil.h"
-#include <memory>
-
-namespace blink {
-
-class Document;
-class WebTaskRunner;
-
-// Represents a set of task runners of the parent (or associated) document's
-// frame. This could be accessed from worker thread(s) and must be initialized
-// on the parent context thread (i.e. MainThread) on construction time, rather
-// than being done lazily.
-class CORE_EXPORT ParentFrameTaskRunners final {
-    WTF_MAKE_NONCOPYABLE(ParentFrameTaskRunners);
-    USING_FAST_MALLOC(ParentFrameTaskRunners);
-public:
-    static std::unique_ptr<ParentFrameTaskRunners> create(Document* document)
-    {
-        return wrapUnique(new ParentFrameTaskRunners(document));
-    }
-
-    ~ParentFrameTaskRunners();
-
-    WebTaskRunner* getUnthrottledTaskRunner();
-    WebTaskRunner* getTimerTaskRunner();
-    WebTaskRunner* getLoadingTaskRunner();
-
-private:
-    ParentFrameTaskRunners(Document*);
-
-    std::unique_ptr<WebTaskRunner> m_unthrottledTaskRunner;
-    std::unique_ptr<WebTaskRunner> m_timerTaskRunner;
-    std::unique_ptr<WebTaskRunner> m_loadingTaskRunner;
-};
-
-} // namespace blink
-
-#endif // ParentFrameTaskRunners_h