Revert 115997 - Replace MessageLoop::DeleteSoon implementation with one that uses base::Bind.

base/message_loop_helpers.h

-// Copyright (c) 2011 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 BASE_MESSAGE_LOOP_HELPERS_H_
-#define BASE_MESSAGE_LOOP_HELPERS_H_
-#pragma once
-
-#include "base/basictypes.h"
-
-namespace tracked_objects {
-class Location;
-}
-
-namespace base {
-
-namespace subtle {
-template <class T, class R> class DeleteHelperInternal;
-}
-
-// This is a template helper which uses a function indirection to erase T from
-// the function signature while still remembering it so we can call the correct
-// destructor. We use this trick so we don't need to include bind.h in a
-// header file. We also embed the function in a class to make it easier for
-// users of DeleteSoon to declare the helper as a friend.
-template <class T>
-class DeleteHelper {
- private:
-  // TODO(dcheng): Move the return type back to a function template parameter.
-  template <class T2, class R> friend class subtle::DeleteHelperInternal;
-
-  static void DoDelete(const void* object) {
-    delete reinterpret_cast<const T*>(object);
-  }
-
-  DISALLOW_COPY_AND_ASSIGN(DeleteHelper);
-};
-
-namespace subtle {
-
-// An internal MessageLoop-like class helper for DeleteHelper. We don't want to
-// expose DoDelete directly since the void* argument makes it possible to pass
-// an object of the wrong type to delete. Instead, we force callers to go
-// through DeleteHelperInternal for type safety. MessageLoop-like classes which
-// expose a DeleteSoon method should friend this class and implement a
-// DeleteSoonInternal method with the following signature:
-// bool(const tracked_objects::Location&,
-//      void(*deleter)(const void*),
-//      void* object)
-// An implementation of DeleteSoonInternal should simply create a base::Closure
-// from (deleter, object) and return the result of posting the task.
-template <class T, class ReturnType>
-class DeleteHelperInternal {
- public:
-  template <class MessageLoopType>
-  static ReturnType DeleteOnMessageLoop(
-      MessageLoopType* message_loop,
-      const tracked_objects::Location& from_here,
-      const T* object) {
-    return message_loop->DeleteSoonInternal(from_here,
-                                            &DeleteHelper<T>::DoDelete,
-                                            object);
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(DeleteHelperInternal);
-};
-
-}  // namespace subtle
-
-}  // namespace base
-
-#endif  // BASE_MESSAGE_LOOP_HELPERS_H_