Add more IPC unit tests:

remoting/host/desktop_process.cc

 // Copyright (c) 2012 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.
 //
 // This file implements the Windows service controlling Me2Me host processes
 // running within user sessions.
 
 #include "remoting/host/desktop_process.h"
 
 #include "base/bind.h"
@@ skipping 53 matching lines @@
   return handled;
 }
 
 void DesktopProcess::OnChannelConnected(int32 peer_pid) {
   DCHECK(caller_task_runner_->BelongsToCurrentThread());
 
   VLOG(1) << "IPC: desktop <- daemon (" << peer_pid << ")";
 }
 
 void DesktopProcess::OnChannelError() {
-  DCHECK(caller_task_runner_->BelongsToCurrentThread());
-
   // Shutdown the desktop process.
   daemon_channel_.reset();
-  desktop_agent_->Stop();
-  desktop_agent_ = NULL;
+  if (desktop_agent_) {
+    desktop_agent_->Stop();
+    desktop_agent_ = NULL;
+  }
+
   caller_task_runner_ = NULL;
 }
 
 bool DesktopProcess::Start(
     scoped_ptr<DesktopEnvironmentFactory> desktop_environment_factory) {
   DCHECK(caller_task_runner_->BelongsToCurrentThread());
   DCHECK(!desktop_environment_factory_);
   DCHECK(desktop_environment_factory);
 
   desktop_environment_factory_ = desktop_environment_factory.Pass();
@@ skipping 54 matching lines @@
 }
 
 void DesktopProcess::OnCrash(const std::string& function_name,
                              const std::string& file_name,
                              const int& line_number) {
   // The daemon requested us to crash the process.
   CHECK(false);
 }
 
 } // namespace remoting