Introduce WorkletGlobalScopeProxy interface.

third_party/WebKit/Source/modules/compositorworker/CompositorWorkletGlobalScope.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 CompositorWorkletGlobalScope_h
+#define CompositorWorkletGlobalScope_h
+
+#include "modules/worklet/ThreadedWorkletGlobalScope.h"
+
+namespace blink {
+
+class CompositorWorkletGlobalScope : public ThreadedWorkletGlobalScope {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    static CompositorWorkletGlobalScope* create(const KURL&, const String& userAgent, PassRefPtr<SecurityOrigin>, v8::Isolate*);
+    ~CompositorWorkletGlobalScope() override;
+
+private:
+    CompositorWorkletGlobalScope(const KURL&, const String& userAgent, PassRefPtr<SecurityOrigin>, v8::Isolate*);
+};
+
+} // namespace blink
+
+#endif // CompositorWorkletGlobalScope_h