forwarder2: Make the Forwarder instances operate on a single thread.

tools/android/forwarder2/host_controller.h

 // 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.
 
 #ifndef TOOLS_ANDROID_FORWARDER2_HOST_CONTROLLER_H_
 #define TOOLS_ANDROID_FORWARDER2_HOST_CONTROLLER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 67 matching lines @@
   const int adb_port_;
   // Used to notify the controller when the process is killed.
   const int global_exit_notifier_fd_;
   scoped_ptr<Socket> adb_control_socket_;
   // Used to cancel the pending blocking IO operations when the host controller
   // instance is deleted.
   scoped_ptr<PipeNotifier> delete_controller_notifier_;
   // Task runner used for deletion set at deletion time (i.e. the object is
   // deleted on the same thread it is created on).
   const scoped_refptr<base::SingleThreadTaskRunner> deletion_task_runner_;
-  // Note that this thread must outlive |forwarders_manager_| below. The
-  // ForwardersManager's internal delegate (outliving ForwardersManager) may
-  // post a task to this thread when it gets deleted. Also note that
-  // base::Thread joins on destruction which means that ~Thread() will only
-  // return after it executed all the tasks enqueued in its message loop. This
-  // also means that it is guaranteed that all the Forwarder instances owned by
-  // the ForwardersManager's internal delegate are destructed before
-  // ~HostController() returns.
   base::Thread thread_;
   ForwardersManager forwarders_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(HostController);
 };
 
 }  // namespace forwarder2
 
 #endif  // TOOLS_ANDROID_FORWARDER2_HOST_CONTROLLER_H_