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

third_party/WebKit/Source/platform/scheduler/child/scheduler_tqm_delegate_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 THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_SCHEDULER_TQM_DELEGATE_IMPL_H_
 #define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_SCHEDULER_TQM_DELEGATE_IMPL_H_
 
 #include <memory>
 
+#include "base/callback.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/time/tick_clock.h"
 #include "platform/scheduler/child/scheduler_tqm_delegate.h"
 
 namespace blink {
 namespace scheduler {
 
 class BLINK_PLATFORM_EXPORT SchedulerTqmDelegateImpl
     : public SchedulerTqmDelegate {
  public:
   // |message_loop| is not owned and must outlive the lifetime of this object.
   static scoped_refptr<SchedulerTqmDelegateImpl> Create(
       base::MessageLoop* message_loop,
       std::unique_ptr<base::TickClock> time_source);
 
   // SchedulerTqmDelegate implementation
   void SetDefaultTaskRunner(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner) override;
   void RestoreDefaultTaskRunner() override;
   bool PostDelayedTask(const tracked_objects::Location& from_here,
-                       const base::Closure& task,
+                       base::Closure task,
                        base::TimeDelta delay) override;
   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
-                                  const base::Closure& task,
+                                  base::Closure task,
                                   base::TimeDelta delay) override;
   bool RunsTasksOnCurrentThread() const override;
   bool IsNested() const override;
   void AddNestingObserver(
       base::MessageLoop::NestingObserver* observer) override;
   void RemoveNestingObserver(
       base::MessageLoop::NestingObserver* observer) override;
   base::TimeTicks NowTicks() override;
 
  protected:
   ~SchedulerTqmDelegateImpl() override;
 
  private:
   SchedulerTqmDelegateImpl(base::MessageLoop* message_loop,
                            std::unique_ptr<base::TickClock> time_source);
 
   // Not owned.
   base::MessageLoop* message_loop_;
   scoped_refptr<SingleThreadTaskRunner> message_loop_task_runner_;
   std::unique_ptr<base::TickClock> time_source_;
 
   DISALLOW_COPY_AND_ASSIGN(SchedulerTqmDelegateImpl);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_SCHEDULER_TQM_DELEGATE_IMPL_H_