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

mojo/package_manager/content_handler_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/bind.h"
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
@@ skipping 57 matching lines @@
   base::MessageLoop::current()->QuitWhenIdle();
 }
 
 class TestContentHandler : public ContentHandler, public ApplicationDelegate {
  public:
   TestContentHandler(ApplicationConnection* connection,
                      InterfaceRequest<ContentHandler> request)
       : binding_(this, request.Pass()) {}
 
   // ContentHandler:
-  void StartApplication(InterfaceRequest<Application> application_request,
-                        URLResponsePtr response) override {
+  void StartApplication(
+      InterfaceRequest<Application> application_request,
+      URLResponsePtr response,
+      const Callback<void()>& destruct_callback) override {
     apps_.push_back(new ApplicationImpl(this, application_request.Pass()));
+    destruct_callback.Run();
   }
 
  private:
   StrongBinding<ContentHandler> binding_;
   ScopedVector<ApplicationImpl> apps_;
 
   DISALLOW_COPY_AND_ASSIGN(TestContentHandler);
 };
 
 class TestApplicationLoader : public shell::ApplicationLoader,
@@ skipping 218 matching lines @@
   params->SetTargetURL(GURL("test:test"));
   params->set_connect_callback(
       [&content_handler_id](uint32_t t) { content_handler_id = t; });
   application_manager_->ConnectToApplication(params.Pass());
   EXPECT_EQ(0u, content_handler_id);
 }
 
 }  // namespace test
 }  // namespace package_manager
 }  // namespace mojo