Task Scheduler.

base/task_scheduler/sequence_sort_key.h

Index: base/task_scheduler/sequence_sort_key.h
diff --git a/base/task_scheduler/sequence_sort_key.h b/base/task_scheduler/sequence_sort_key.h
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+// Copyright 2016 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_TASK_SCHEDULER_SEQUENCE_SORT_KEY_H_
+#define BASE_TASK_SCHEDULER_SEQUENCE_SORT_KEY_H_
+
+#include "base/base_export.h"
+#include "base/gtest_prod_util.h"
+#include "base/task_scheduler/task_traits.h"
+#include "base/time/time.h"
+
+namespace base {
+namespace task_scheduler {
+
+// A SequenceSortKey determines the position of a Sequence in a PriorityQueue.
+// Contrary to a Sequence, which can be modified when it is inside a
+// PriorityQueue, a SequenceSortKey is immutable.
+class BASE_EXPORT SequenceSortKey {
+ public:
+  SequenceSortKey();
+  SequenceSortKey(TaskPriority priority, TimeTicks next_task_post_time);
+
+  // Returns true if the the sequence associated with this sort key must run
+  // after the sequence associated with |other|.
+  bool operator<(const SequenceSortKey& other) const;
+
+  // Used for testing.
+  bool operator==(const SequenceSortKey& other) const;
+
+  TaskPriority priority() const { return priority_; }
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(TaskSchedulerSequenceTest, GetSequenceSortKey);
+
+  // Highest task priority in the sequence at the time this sort key is created.
+  TaskPriority priority_;
+
+  // Post time of the next task to run in the sequence.
+  TimeTicks next_task_post_time_;
+};
+
+}  // namespace task_scheduler
+}  // namespace base
+
+#endif  // BASE_TASK_SCHEDULER_SEQUENCE_SORT_KEY_H_