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

mojo/fetcher/about_fetcher_unittest.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 "base/at_exit.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
 #include "base/run_loop.h"
@@ skipping 33 matching lines @@
     return true;
   }
 
   // Overridden from InterfaceFactory<ContentHandler>:
   void Create(ApplicationConnection* connection,
               InterfaceRequest<ContentHandler> request) override {
     bindings_.AddBinding(this, request.Pass());
   }
 
   // Overridden from ContentHandler:
-  void StartApplication(InterfaceRequest<Application> application,
-                        URLResponsePtr response) override {
+  void StartApplication(
+      InterfaceRequest<Application> application,
+      URLResponsePtr response,
+      const Callback<void()>& destruct_callback) override {
     response_number_++;
     latest_response_ = response.Pass();
+    destruct_callback.Run();
 
     // Drop |application| request. This results in the application manager
     // dropping the ServiceProvider interface request provided by the client
     // who made the ConnectToApplication() call. Therefore the client could
     // listen for connection error of the ServiceProvider interface to learn
     // that StartApplication() has been called.
   }
 
   size_t response_number_;
   URLResponsePtr latest_response_;
@@ skipping 98 matching lines @@
   const URLResponse* response = html_content_handler()->latest_response();
   EXPECT_EQ("about:some_unrecognized_url", response->url);
   EXPECT_EQ(404u, response->status_code);
   EXPECT_EQ("text/html", response->mime_type);
   EXPECT_FALSE(response->body.is_valid());
 }
 
 }  // namespace
 }  // namespace fetcher
 }  // namespace mojo