Introduce WorkletGlobalScopeProxy interface.

third_party/WebKit/Source/modules/worklet/ThreadedWorkletGlobalScope.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 ThreadedWorkletGlobalScope_h
+#define ThreadedWorkletGlobalScope_h
+
+#include "core/workers/WorkletGlobalScope.h"
+
+namespace blink {
+
+class ThreadedWorkletGlobalScope : public WorkletGlobalScope {
+public:
+    ~ThreadedWorkletGlobalScope() override;
+
+    void addConsoleMessage(ConsoleMessage*) final;
+
+protected:
+    ThreadedWorkletGlobalScope(const KURL&, const String& userAgent, PassRefPtr<SecurityOrigin>, v8::Isolate*);
+};
+
+} // namespace blink
+
+#endif // ThreadedWorkletGlobalScope_h