Add TestMockTimeTaskRunner in base/test.

base/test/test_mock_time_task_runner.h

Index: base/test/test_mock_time_task_runner.h
diff --git a/base/test/test_mock_time_task_runner.h b/base/test/test_mock_time_task_runner.h
new file mode 100644
index 0000000000000000000000000000000000000000..0f33e97c82522511fe06558369bd9ef7d81d7aca
--- /dev/null
+++ b/base/test/test_mock_time_task_runner.h
@@ -0,0 +1,117 @@
+// Copyright 2014 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_TEST_MOCK_TIME_TASK_RUNNER_H_
+#define BASE_TEST_MOCK_TIME_TASK_RUNNER_H_
+
+#include <queue>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"

[bartfab (slow), 2015/01/08 14:14:35]

Nit: Not used.

[engedy, 2015/01/08 16:41:26]

Done.

+#include "base/memory/scoped_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "base/synchronization/lock.h"
+#include "base/test/test_pending_task.h"
+#include "base/time/tick_clock.h"
+#include "base/time/time.h"
+
+namespace base {
+
+// Runs pending tasks in the order of the tasks' post time + delay, and keeps
+// track of a mock (virtual) tick clock time that can be fast forwarded.
+//
+// TestMockTimeTaskRunner has the following properties:
+//
+//   - PostTask() and friends can be called from any thread, but the rest of the
+//     methods must be called on the same thread the TaskRunner was created on.
+//   - It allows for reentrancy, in that it handles the running of tasks that in
+//     turn call back into it (e.g., to post more tasks).
+//   - Tasks are stored in a priority queue, and executed in the increasing
+//     order of post time + delay.
+//   - Non-nestable tasks are not supported.
+//   - Tasks aren't guaranteed to be destroyed immediately after they're run.
+//
+// This is a slightly more sophisticated version of TestSimpleTaskRunner, in
+// that it supports running delayed tasks in the correct temporal order.
+class TestMockTimeTaskRunner : public base::SingleThreadTaskRunner {
+ public:
+  TestMockTimeTaskRunner();
+
+  // Fast forwards virtual time by |delta|, causing all tasks with a remaining

[bartfab (slow), 2015/01/08 14:14:35]

Nit: s/Fast forwards/Fast-forwards/

[engedy, 2015/01/08 16:41:26]

Done. Also one more place in the class comment.

+  // delay of less than or equal to |delta| to be executed.

[bartfab (slow), 2015/01/08 14:14:35]

Nit: s/of //

[engedy, 2015/01/08 16:41:25]

Done.

+  void FastForwardBy(base::TimeDelta delta);
+
+  // Fast forwards virtual time just until all tasks are executed.

[bartfab (slow), 2015/01/08 14:14:35]

Nit: s/Fast forwards/Fast-forwards/

[engedy, 2015/01/08 16:41:26]

Done.

+  void FastForwardUntilNoTasksRemain();
+
+  // Executes all tasks having no remaining delay. No virtual time will elapse.

[bartfab (slow), 2015/01/08 14:14:34]

Nit: Could you add one more sentence which explicitly states that delayed tasks
will remain enqueued?

[engedy, 2015/01/08 16:41:26]

Done.

+  void RunUntilIdle();
+
+  // Returns the current virtual time.
+  TimeTicks GetCurrentMockTime() const;
+
+  // Returns a TickClock that uses the mock time of |this| as its time source.
+  scoped_ptr<TickClock> GetMockTickClock() const;
+
+  bool HasPendingTask() const;
+  TimeDelta NextPendingTaskDelay() const;
+
+  // SingleThreadTaskRunner:
+  virtual bool RunsTasksOnCurrentThread() const override;
+  virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
+                               const base::Closure& task,
+                               TimeDelta delay) override;
+  virtual bool PostNonNestableDelayedTask(
+      const tracked_objects::Location& from_here,
+      const base::Closure& task,
+      TimeDelta delay) override;
+
+ protected:
+  virtual ~TestMockTimeTaskRunner();
+
+  // Called before the next task to run is selected, so that subclasses have a
+  // last chance to make sure all tasks are posted.
+  virtual void OnBeforeSelectingTask();
+
+  // Called after the current mock time had been incremented so that subclasses

[bartfab (slow), 2015/01/08 14:14:34]

Nit: s/had/has/

[engedy, 2015/01/08 16:41:26]

Done.

+  // can react to the passing of time.
+  virtual void OnAfterTimePasses();

[bartfab (slow), 2015/01/08 14:14:34]

Nit: s/Passes/Passed/

[engedy, 2015/01/08 16:41:25]

Done.

+
+  // Called after each task is run so that subclasses may perform additional
+  // activities, e.g., pumping out tasks from additional task runners.

[bartfab (slow), 2015/01/08 14:14:35]

Nit: s/pumping out tasks from/pump/

[engedy, 2015/01/08 16:41:26]

Done.

+  virtual void OnAfterRunningTask();

[bartfab (slow), 2015/01/08 14:14:35]

Nit: s/RunningTask/TaskRun/

[engedy, 2015/01/08 16:41:26]

Done.

+
+ private:
+  // Predicate that defines a strict weak temporal ordering of tasks.
+  class TemporalOrder {
+   public:
+    bool operator()(const TestPendingTask& first_task,
+                    const TestPendingTask& second_task) const;
+  };
+
+  typedef std::priority_queue<TestPendingTask,
+                              std::vector<TestPendingTask>,

[bartfab (slow), 2015/01/08 14:14:35]

Nit: #include <vector>

[engedy, 2015/01/08 16:41:26]

Done.

+                              TemporalOrder> TaskPriorityQueue;
+
+  // Returns the |next_task| to run if there is any with a running time that is
+  // at most |reference| + |max_delta|. This additional complexity is required
+  // so that |max_delta| == TimeDelta::Max() can be supported.
+  bool DequeueNextTask(const base::TimeTicks& reference,
+                       const base::TimeDelta& max_delta,
+                       TestPendingTask* next_task);
+
+  base::ThreadChecker thread_checker_;

[bartfab (slow), 2015/01/08 14:14:35]

Nit: #include "base/threading/thread_checker.h"

[engedy, 2015/01/08 16:41:26]

Done.

+  base::TimeTicks now_;
+
+  // Temporally ordered heap of pending tasks. Must only be accessed while the
+  // |tasks_lock_| is acquired.

[bartfab (slow), 2015/01/08 14:14:34]

Nit: s/acquired/held/

[engedy, 2015/01/08 16:41:26]

Done.

+  TaskPriorityQueue tasks_;
+  base::Lock tasks_lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestMockTimeTaskRunner);
+};
+
+}  // namespace base
+
+#endif  // BASE_TEST_TEMPORAL_ORDER_TASK_RUNNER_H_