Delete unused TaskRunner abstraction.

webrtc/base/taskparent.h

-/*
- *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef WEBRTC_BASE_TASKPARENT_H__
-#define WEBRTC_BASE_TASKPARENT_H__
-
-#include <memory>
-#include <set>
-
-#include "webrtc/base/checks.h"
-#include "webrtc/base/constructormagic.h"
-
-namespace rtc {
-
-class Task;
-class TaskRunner;
-
-class TaskParent {
- public:
-  TaskParent(Task *derived_instance, TaskParent *parent);
-  explicit TaskParent(TaskRunner *derived_instance);
-  virtual ~TaskParent();
-
-  TaskParent *GetParent() { return parent_; }
-  TaskRunner *GetRunner() { return runner_; }
-
-  bool AllChildrenDone();
-  bool AnyChildError();
-#if RTC_DCHECK_IS_ON
-  bool IsChildTask(Task *task);
-#endif
-
- protected:
-  void OnStopped(Task *task);
-  void AbortAllChildren();
-  TaskParent *parent() {
-    return parent_;
-  }
-
- private:
-  void Initialize();
-  void OnChildStopped(Task *child);
-  void AddChild(Task *child);
-
-  TaskParent *parent_;
-  TaskRunner *runner_;
-  bool child_error_;
-  typedef std::set<Task *> ChildSet;
-  std::unique_ptr<ChildSet> children_;
-  RTC_DISALLOW_COPY_AND_ASSIGN(TaskParent);
-};
-
-
-} // namespace rtc
-
-#endif  // WEBRTC_BASE_TASKPARENT_H__