Make PendingTask move-only and pass it by value on retaining params

components/scheduler/base/task_queue_impl.h

 // Copyright 2015 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 CONTENT_RENDERER_SCHEDULER_BASE_TASK_QUEUE_IMPL_H_
 #define CONTENT_RENDERER_SCHEDULER_BASE_TASK_QUEUE_IMPL_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 202 matching lines @@
   bool PostImmediateTaskImpl(const tracked_objects::Location& from_here,
                              const base::Closure& task,
                              TaskType task_type);
   bool PostDelayedTaskImpl(const tracked_objects::Location& from_here,
                            const base::Closure& task,
                            base::TimeDelta delay,
                            TaskType task_type);
 
   // Push the task onto the |delayed_incoming_queue|. Lock-free main thread
   // only fast path.
-  void PushOntoDelayedIncomingQueueFromMainThread(const Task& pending_task,
+  void PushOntoDelayedIncomingQueueFromMainThread(Task pending_task,
                                                   base::TimeTicks now);
 
   // Push the task onto the |delayed_incoming_queue|.  Slow path from other
   // threads.
-  void PushOntoDelayedIncomingQueueLocked(const Task& pending_task);
+  void PushOntoDelayedIncomingQueueLocked(Task pending_task);
 
-  void ScheduleDelayedWorkTask(const Task& pending_task);
+  void ScheduleDelayedWorkTask(Task pending_task);
 
   // Enqueues any delayed tasks which should be run now on the
   // |delayed_work_queue|.  Must be called from the main thread.
   void MoveReadyDelayedTasksToDelayedWorkQueue(LazyNow* lazy_now);
 
   void MoveReadyImmediateTasksToImmediateWorkQueueLocked();
 
   // Note this does nothing if its not called from the main thread.
   void PumpQueueLocked(bool may_post_dowork);
 
   // Returns true if |task| is older than the oldest incoming immediate task.
   // NOTE |any_thread_lock_| must be locked.
   bool TaskIsOlderThanQueuedImmediateTasksLocked(const Task* task);
 
   // Returns true if |task| is older than the oldest delayed task.  Must be
   // called from the main thread.
   bool TaskIsOlderThanQueuedDelayedTasks(const Task* task);
 
   // NOTE |any_thread_lock_| must be locked.
   bool ShouldAutoPumpImmediateQueueLocked(bool should_trigger_wakeup,
                                           const Task* previous_task);
 
   //  Must be called from the main thread.
   bool ShouldAutoPumpDelayedQueue(bool should_trigger_wakeup,
                                   const Task* previous_task);
 
   // Push the task onto the |immediate_incoming_queue| and for auto pumped
   // queues it calls MaybePostDoWorkOnMainRunner if the Incoming queue was
   // empty.
-  void PushOntoImmediateIncomingQueueLocked(const Task& pending_task);
+  void PushOntoImmediateIncomingQueueLocked(Task pending_task);
 
   void TraceQueueSize(bool is_locked) const;
   static void QueueAsValueInto(const std::queue<Task>& queue,
                                base::trace_event::TracedValue* state);
   static void QueueAsValueInto(const std::priority_queue<Task>& queue,
                                base::trace_event::TracedValue* state);
   static void TaskAsValueInto(const Task& task,
                               base::trace_event::TracedValue* state);
 
   const base::PlatformThreadId thread_id_;
@@ skipping 29 matching lines @@
   const bool should_notify_observers_;
   const bool should_report_when_execution_blocked_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskQueueImpl);
 };
 
 }  // namespace internal
 }  // namespace scheduler
 
 #endif  // CONTENT_RENDERER_SCHEDULER_BASE_TASK_QUEUE_IMPL_H_