[mojo-edk] Simplify multiprocess pipe bootstrap

mash/shell/shell_application_delegate.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 "mash/shell/shell_application_delegate.h"
 
 #include "base/bind.h"
 #include "mojo/shell/public/cpp/connection.h"
 #include "mojo/shell/public/cpp/shell.h"
 
@@ skipping 99 matching lines @@
   DCHECK(connections_.end() != connection);
   connections_.erase(connection);
 }
 
 void ShellApplicationDelegate::StartRestartableService(
     const std::string& url,
     const base::Closure& restart_callback) {
   // TODO(beng): This would be the place to insert logic that counted restarts
   //             to avoid infinite crash-restart loops.
   scoped_ptr<mojo::Connection> connection = shell_->Connect(url);
-  connection->SetRemoteServiceProviderConnectionErrorHandler(restart_callback);
-  connections_[url] = std::move(connection);
+  // Note: |connection| may be null if we've lost our connection to the shell.
+  if (connection) {
+    connection->SetRemoteServiceProviderConnectionErrorHandler(
+        restart_callback);
+    connections_[url] = std::move(connection);
+  }
 }
 
 }  // namespace shell
 }  // namespace main