ServiceWorker: Introduce SWMessageSender in order to mock IPC messaging

content/renderer/service_worker/embedded_worker_context_client.h

Index: content/renderer/service_worker/embedded_worker_context_client.h
diff --git a/content/renderer/service_worker/embedded_worker_context_client.h b/content/renderer/service_worker/embedded_worker_context_client.h
index d12268de92b41fdf455b6343719879315fc337a0..0634434bf57e2b0051ddade933b5844c810e9ac7 100644
--- a/content/renderer/service_worker/embedded_worker_context_client.h
+++ b/content/renderer/service_worker/embedded_worker_context_client.h
@@ -25,6 +25,7 @@ class WebServiceWorkerProvider;
 
 namespace content {
 
+class ServiceWorkerMessageSender;
 class ServiceWorkerProviderContext;
 class ServiceWorkerScriptContext;
 class ThreadSafeSender;
@@ -134,7 +135,7 @@ class EmbeddedWorkerContextClient
   base::SingleThreadTaskRunner* main_thread_task_runner() const {
     return main_thread_task_runner_.get();
   }
-  ThreadSafeSender* thread_safe_sender() { return sender_.get(); }
+  ServiceWorkerMessageSender* sender() { return sender_.get(); }
 
  private:
   void OnMessageToWorker(int thread_id,
@@ -148,7 +149,7 @@ class EmbeddedWorkerContextClient
   const GURL service_worker_scope_;
   const GURL script_url_;
   const int worker_devtools_agent_route_id_;
-  scoped_refptr<ThreadSafeSender> sender_;
+  scoped_refptr<ServiceWorkerMessageSender> sender_;
   scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
   scoped_refptr<base::TaskRunner> worker_task_runner_;