compositor-worker: Add CompositorProxyClient worker client of CompositorWorker.

third_party/WebKit/Source/core/dom/CompositorProxyClient.cpp

+// 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.
+
+#include "core/dom/CompositorProxyClient.h"
+
+#include "platform/TraceEvent.h"
+
+namespace blink {
+
+CompositorProxyClient* CompositorProxyClient::from(WorkerClients* clients)
+{
+    return static_cast<CompositorProxyClient*>(Supplement<WorkerClients>::from(clients, supplementName()));
+}
+
+const char* CompositorProxyClient::supplementName()
+{
+    return "CompositorProxyClient";
+}
+
+void provideCompositorProxyClientTo(WorkerClients* clients, CompositorProxyClient* client)
+{
+    clients->provideSupplement(CompositorProxyClient::supplementName(), client);
+}
+
+} // namespace blink