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

components/scheduler/base/work_queue.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_WORK_QUEUE_H_
 #define CONTENT_RENDERER_SCHEDULER_BASE_WORK_QUEUE_H_
 
 #include <stddef.h>
 
 #include <set>
@@ skipping 31 matching lines @@
   // If the |work_queue_| isn't empty, |enqueue_order| gets set to the enqueue
   // order of the front task and the function returns true.  Otherwise the
   // function returns false.
   bool GetFrontTaskEnqueueOrder(EnqueueOrder* enqueue_order) const;
 
   // Returns the first task in this queue or null if the queue is empty.
   const TaskQueueImpl::Task* GetFrontTask() const;
 
   // Pushes the task onto the |work_queue_| and informs the WorkQueueSets if
   // the head changed.
-  void Push(const TaskQueueImpl::Task& task);
+  void Push(TaskQueueImpl::Task task);
 
   // Pushes the task onto the |work_queue_|, sets the |enqueue_order| and
   // informs the WorkQueueSets if the head changed.
-  void PushAndSetEnqueueOrder(const TaskQueueImpl::Task& task,
+  void PushAndSetEnqueueOrder(TaskQueueImpl::Task task,
                               EnqueueOrder enqueue_order);
 
   // Swap the |work_queue_| with |incoming_queue| and informs the
   // WorkQueueSets if the head changed. Assumes |task_queue_->any_thread_lock_|
   // is locked.
   void SwapLocked(std::queue<TaskQueueImpl::Task>& incoming_queue);
 
   size_t Size() const { return work_queue_.size(); }
 
   // Pulls a task off the |work_queue_| and informs the WorkQueueSets.
@@ skipping 14 matching lines @@
   // than the front task of |other_queue|. Both queue are assumed to be
   // non-empty.
   bool ShouldRunBefore(const WorkQueue* other_queue) const;
 
  private:
   std::queue<TaskQueueImpl::Task> work_queue_;
   WorkQueueSets* work_queue_sets_;  // NOT OWNED.
   TaskQueueImpl* task_queue_;       // NOT OWNED.
   size_t work_queue_set_index_;
   const char* name_;
+
+  DISALLOW_COPY_AND_ASSIGN(WorkQueue);
 };
 
 }  // namespace internal
 }  // namespace scheduler
 
 #endif  // CONTENT_RENDERER_SCHEDULER_BASE_WORK_QUEUE_H_