Fix hangs in Mandoline page cycler on Linux with --enable-multiprocess.

components/html_viewer/layout_test_content_handler_impl.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 COMPONENTS_HTML_VIEWER_LAYOUT_TEST_CONTENT_HANDLER_IMPL_H_
 #define COMPONENTS_HTML_VIEWER_LAYOUT_TEST_CONTENT_HANDLER_IMPL_H_
 
 #include "components/html_viewer/content_handler_impl.h"
 #include "components/html_viewer/html_factory.h"
 #include "components/test_runner/web_test_proxy.h"
@@ skipping 19 matching lines @@
                                test_runner::WebTestInterfaces* test_interfaces,
                                WebTestDelegateImpl* test_delegate);
   ~LayoutTestContentHandlerImpl() override;
 
  private:
   using WebWidgetProxy =
       test_runner::WebTestProxy<HTMLWidgetRootLocal,
                                 HTMLWidgetRootLocal::CreateParams*>;
 
   // ContentHandler:
-  void StartApplication(mojo::InterfaceRequest<mojo::Application> request,
-                        mojo::URLResponsePtr response) override;
+  void StartApplication(
+      mojo::InterfaceRequest<mojo::Application> request,
+      mojo::URLResponsePtr response,
+      const mojo::Callback<void()>& destruct_callback) override;
 
   // HTMLFactory
   HTMLFrame* CreateHTMLFrame(HTMLFrame::CreateParams* params) override;
   HTMLWidgetRootLocal* CreateHTMLWidgetRootLocal(
       HTMLWidgetRootLocal::CreateParams* params) override;
 
   test_runner::WebTestInterfaces* test_interfaces_;
   WebTestDelegateImpl* test_delegate_;
   WebWidgetProxy* web_widget_proxy_;
+  scoped_ptr<mojo::AppRefCount> app_refcount_;
 
   DISALLOW_COPY_AND_ASSIGN(LayoutTestContentHandlerImpl);
 };
 
 }  // namespace html_viewer
 
 #endif  // COMPONENTS_HTML_VIEWER_LAYOUT_TEST_CONTENT_HANDLER_IMPL_H_