Create an API around UtilityProcessHost and use that from chrome.

content/public/browser/utility_process_host_client.h

+// Copyright (c) 2012 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 CONTENT_PUBLIC_BROWSER_UTILITY_PROCESS_HOST_CLIENT_H_
+#define CONTENT_PUBLIC_BROWSER_UTILITY_PROCESS_HOST_CLIENT_H_
+#pragma once
+
+#include "base/memory/ref_counted.h"
+#include "content/common/content_export.h"
+
+namespace IPC {
+class Message;
+}
+
+namespace content {
+
+// An interface to be implemented by consumers of the utility process to
+// get results back.  All functions are called on the thread passed along
+// to UtilityProcessHost.
+class UtilityProcessHostClient
+    : public base::RefCountedThreadSafe<UtilityProcessHostClient> {
+ public:
+  // Called when the process has crashed.
+  virtual void OnProcessCrashed(int exit_code) {}
+
+  // Allow the client to filter IPC messages.
+  virtual bool OnMessageReceived(const IPC::Message& message) = 0;
+
+ protected:
+  friend class base::RefCountedThreadSafe<UtilityProcessHostClient>;
+
+  virtual ~UtilityProcessHostClient() {}
+};
+
+};  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_UTILITY_PROCESS_HOST_CLIENT_H_