Convert utility process extension Unpacker IPC to mojo

extensions/test/test_content_utility_client.h

 // 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.
 
 #ifndef EXTENSIONS_TEST_TEST_CONTENT_UTILITY_CLIENT_H_
 #define EXTENSIONS_TEST_TEST_CONTENT_UTILITY_CLIENT_H_
 
 #include "content/public/utility/content_utility_client.h"
 #include "extensions/utility/utility_handler.h"
 
 namespace extensions {
 
 class TestContentUtilityClient : public content::ContentUtilityClient {
  public:
   TestContentUtilityClient();
   ~TestContentUtilityClient() override;
 
-  // ContentUtilityClient implementation
+  // content::ContentUtilityClient:
   void UtilityThreadStarted() override;
+  void ExposeInterfacesToBrowser(
+      service_manager::InterfaceRegistry* registry) override;
   bool OnMessageReceived(const IPC::Message& message) override;
 
  private:
   UtilityHandler utility_handler_;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_TEST_TEST_CONTENT_UTILITY_CLIENT_H_