[POC-WIP] Link window focus tokens with ExecutionContext.

Source/modules/serviceworkers/ServiceWorkerClient.h

 // Copyright 2014 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 ServiceWorkerClient_h
 #define ServiceWorkerClient_h
 
+#include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "bindings/core/v8/SerializedScriptValue.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Forward.h"
 
 namespace blink {
 
+class ExecutionContext;
+class ScriptState;
+
 class ServiceWorkerClient final : public GarbageCollected<ServiceWorkerClient>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static ServiceWorkerClient* create(unsigned id);
 
     // ServiceWorkerClient.idl
     void postMessage(ExecutionContext*, PassRefPtr<SerializedScriptValue> message, const MessagePortArray*, ExceptionState&);
+    ScriptPromise focus(ScriptState*);
 
     void trace(Visitor*) { }
 
 private:
     explicit ServiceWorkerClient(unsigned id);
 
     unsigned m_id;
 };
 
 } // namespace blink
 
 #endif // ServiceWorkerClient_h