ServiceWorker: Introduce SWMessageSender in order to mock IPC messaging

content/child/service_worker/service_worker_message_sender.cc

+// 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.
+
+#include "content/child/service_worker/service_worker_message_sender.h"
+
+#include "content/child/thread_safe_sender.h"
+
+namespace content {
+
+ServiceWorkerMessageSender::ServiceWorkerMessageSender(
+    ThreadSafeSender* thread_safe_sender)
+    : thread_safe_sender_(thread_safe_sender) {
+}
+
+bool ServiceWorkerMessageSender::Send(IPC::Message* message) {
+  return thread_safe_sender_->Send(message);
+}
+
+ServiceWorkerMessageSender::~ServiceWorkerMessageSender() {
+}
+
+}  // namespace content