compositor-worker: Introduce CompositorWorker.

Source/modules/compositorworker/CompositorWorkerThread.h

+// 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.
+
+#ifndef CompositorWorkerThread_h
+#define CompositorWorkerThread_h
+
+#include "core/workers/WorkerThread.h"
+
+namespace blink {
+
+class WorkerObjectProxy;
+
+class CompositorWorkerThread final : public WorkerThread {
+public:
+    static PassRefPtr<CompositorWorkerThread> create(PassRefPtr<WorkerLoaderProxy>, WorkerObjectProxy&, double timeOrigin, PassOwnPtrWillBeRawPtr<WorkerThreadStartupData>);
+    virtual ~CompositorWorkerThread();
+
+    WorkerObjectProxy& workerObjectProxy() const { return m_workerObjectProxy; }
+
+private:
+    CompositorWorkerThread(PassRefPtr<WorkerLoaderProxy>, WorkerObjectProxy&, double timeOrigin, PassOwnPtrWillBeRawPtr<WorkerThreadStartupData>);
+
+    // WorkerThread:
+    PassRefPtrWillBeRawPtr<WorkerGlobalScope> createWorkerGlobalScope(PassOwnPtrWillBeRawPtr<WorkerThreadStartupData>) override;
+
+    WorkerObjectProxy& m_workerObjectProxy;
+    double m_timeOrigin;
+};
+
+} // namespace blink
+
+#endif // CompositorWorkerThread_h