Pass Callback to TaskRunner by value and consume it on invocation (1)

media/base/fake_single_thread_task_runner.h

 // 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 MEDIA_BASE_FAKE_SINGLE_THREAD_TASK_RUNNER_H_
 #define MEDIA_BASE_FAKE_SINGLE_THREAD_TASK_RUNNER_H_
 
 #include <map>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/test/simple_test_tick_clock.h"
 
 namespace media {
 
 class FakeSingleThreadTaskRunner : public base::SingleThreadTaskRunner {
  public:
   explicit FakeSingleThreadTaskRunner(base::SimpleTestTickClock* clock);
 
   void RunTasks();
 
   // Note: Advances |clock_|.
   void Sleep(base::TimeDelta t);
 
   // base::SingleThreadTaskRunner implementation.
   bool PostDelayedTask(const tracked_objects::Location& from_here,
-                       const base::Closure& task,
+                       base::Closure task,
                        base::TimeDelta delay) final;
 
   bool RunsTasksOnCurrentThread() const final;
 
   // This function is currently not used, and will return false.
   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
-                                  const base::Closure& task,
+                                  base::Closure task,
                                   base::TimeDelta delay) final;
 
  protected:
   ~FakeSingleThreadTaskRunner() final;
 
  private:
   base::SimpleTestTickClock* const clock_;
 
   // A compound key is used to ensure FIFO execution of delayed tasks scheduled
   // for the same point-in-time.  The second part of the key is simply a FIFO
   // sequence number.
   using TaskKey = std::pair<base::TimeTicks, unsigned int>;
 
   // Note: The std::map data structure was chosen because the entire
   // cast_unittests suite performed 20% faster than when using
   // std::priority_queue.  http://crbug.com/530842
   std::map<TaskKey, base::Closure> tasks_;
 
   bool fail_on_next_task_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeSingleThreadTaskRunner);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_FAKE_SINGLE_THREAD_TASK_RUNNER_H_