Mojo: Don't allow closed pipe handles to be sent

mojo/edk/system/remote_message_pipe_bootstrap.cc

 // Copyright 2016 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 "mojo/edk/system/remote_message_pipe_bootstrap.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/macros.h"
 #include "base/thread_task_runner_handle.h"
@@ skipping 14 matching lines @@
   ports::PortName port_name;
 };
 
 }  // namespace
 
 // static
 void RemoteMessagePipeBootstrap::Create(
     NodeController* node_controller,
     ScopedPlatformHandle platform_handle,
     const ports::PortRef& port) {
+  CHECK(node_controller);
+  CHECK(node_controller->io_task_runner());
   if (node_controller->io_task_runner()->RunsTasksOnCurrentThread()) {
     // Owns itself.
     new RemoteMessagePipeBootstrap(
         node_controller, std::move(platform_handle), port);
   } else {
     node_controller->io_task_runner()->PostTask(
         FROM_HERE,
         base::Bind(&RemoteMessagePipeBootstrap::Create,
                    base::Unretained(node_controller),
                    base::Passed(&platform_handle), port));
@@ skipping 93 matching lines @@
   DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
   ShutDown();
 }
 
 void RemoteMessagePipeBootstrap::ShutDownNow() {
   delete this;
 }
 
 }  // namespace edk
 }  // namespace mojo