Add a copy of webrtc's TaskRunner abstraction, which is going to be deleted in webrtc.

third_party/libjingle_xmpp/task_runner/taskparent.cc

+/*
+ *  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.
+ */
+
+#include <algorithm>
+
+#include "third_party/libjingle_xmpp/task_runner/taskparent.h"
+
+#include "third_party/libjingle_xmpp/task_runner/taskrunner.h"
+#include "third_party/libjingle_xmpp/task_runner/task.h"
+#include "third_party/webrtc/base/checks.h"
+
+namespace rtc {
+
+TaskParent::TaskParent(Task* derived_instance, TaskParent *parent)
+    : parent_(parent) {
+  RTC_DCHECK(derived_instance != NULL);
+  RTC_DCHECK(parent != NULL);
+  runner_ = parent->GetRunner();
+  parent_->AddChild(derived_instance);
+  Initialize();
+}
+
+TaskParent::TaskParent(TaskRunner *derived_instance)
+    : parent_(NULL),
+      runner_(derived_instance) {
+  RTC_DCHECK(derived_instance != NULL);
+  Initialize();
+}
+
+TaskParent::~TaskParent() = default;
+
+// Does common initialization of member variables
+void TaskParent::Initialize() {
+  children_.reset(new ChildSet());
+  child_error_ = false;
+}
+
+void TaskParent::AddChild(Task *child) {
+  children_->insert(child);
+}
+
+#if RTC_DCHECK_IS_ON
+bool TaskParent::IsChildTask(Task *task) {
+  RTC_DCHECK(task != NULL);
+  return task->parent_ == this && children_->find(task) != children_->end();
+}
+#endif
+
+bool TaskParent::AllChildrenDone() {
+  for (ChildSet::iterator it = children_->begin();
+       it != children_->end();
+       ++it) {
+    if (!(*it)->IsDone())
+      return false;
+  }
+  return true;
+}
+
+bool TaskParent::AnyChildError() {
+  return child_error_;
+}
+
+void TaskParent::AbortAllChildren() {
+  if (children_->size() > 0) {
+#if RTC_DCHECK_IS_ON
+    runner_->IncrementAbortCount();
+#endif
+
+    ChildSet copy = *children_;
+    for (ChildSet::iterator it = copy.begin(); it != copy.end(); ++it) {
+      (*it)->Abort(true);  // Note we do not wake
+    }
+
+#if RTC_DCHECK_IS_ON
+    runner_->DecrementAbortCount();
+#endif
+  }
+}
+
+void TaskParent::OnStopped(Task *task) {
+  AbortAllChildren();
+  parent_->OnChildStopped(task);
+}
+
+void TaskParent::OnChildStopped(Task *child) {
+  if (child->HasError())
+    child_error_ = true;
+  children_->erase(child);
+}
+
+} // namespace rtc