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

base/task_scheduler/post_task.h

 // Copyright 2016 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_TASK_SCHEDULER_POST_TASK_H_
 #define BASE_TASK_SCHEDULER_POST_TASK_H_
 
 #include <utility>
 
 #include "base/base_export.h"
@@ skipping 52 matching lines @@
 // Prerequisite: A TaskScheduler must have been registered for the current
 // process via TaskScheduler::SetInstance() before the functions below are
 // valid. This is typically done during the initialization phase in each
 // process. If your code is not running in that phase, you most likely don't
 // have to worry about this. You will encounter DCHECKs or nullptr dereferences
 // if this is violated. For tests, prefer base::test::ScopedTaskScheduler.
 
 // Posts |task| to the TaskScheduler. Calling this is equivalent to calling
 // PostTaskWithTraits with plain TaskTraits.
 BASE_EXPORT void PostTask(const tracked_objects::Location& from_here,
-                          const Closure& task);
+                          Closure task);
 
 // Posts |task| to the TaskScheduler. |task| will not run before |delay|
 // expires. Calling this is equivalent to calling PostDelayedTaskWithTraits with
 // plain TaskTraits.
 //
 // Use PostDelayedTaskWithTraits to specify a BACKGROUND priority if the task
 // doesn't have to run as soon as |delay| expires.
 BASE_EXPORT void PostDelayedTask(const tracked_objects::Location& from_here,
-                                 const Closure& task,
+                                 Closure task,
                                  TimeDelta delay);
 
 // Posts |task| to the TaskScheduler and posts |reply| on the caller's execution
 // context (i.e. same sequence or thread and same TaskTraits if applicable) when
 // |task| completes. Calling this is equivalent to calling
 // PostTaskWithTraitsAndReply with plain TaskTraits. Can only be called when
 // SequencedTaskRunnerHandle::IsSet().
 BASE_EXPORT void PostTaskAndReply(const tracked_objects::Location& from_here,
                                   Closure task,
                                   Closure reply);
 
 // Posts |task| to the TaskScheduler and posts |reply| with the return value of
 // |task| as argument on the caller's execution context (i.e. same sequence or
 // thread and same TaskTraits if applicable) when |task| completes. Calling this
 // is equivalent to calling PostTaskWithTraitsAndReplyWithResult with plain
 // TaskTraits. Can only be called when SequencedTaskRunnerHandle::IsSet().
 template <typename TaskReturnType, typename ReplyArgType>
 void PostTaskAndReplyWithResult(const tracked_objects::Location& from_here,
                                 Callback<TaskReturnType(void)> task,
                                 Callback<void(ReplyArgType)> reply) {
   PostTaskWithTraitsAndReplyWithResult(from_here, TaskTraits(), std::move(task),
                                        std::move(reply));
 }
 
 // Posts |task| with specific |traits| to the TaskScheduler.
 BASE_EXPORT void PostTaskWithTraits(const tracked_objects::Location& from_here,
                                     const TaskTraits& traits,
-                                    const Closure& task);
+                                    Closure task);
 
 // Posts |task| with specific |traits| to the TaskScheduler. |task| will not run
 // before |delay| expires.
 //
 // Specify a BACKGROUND priority via |traits| if the task doesn't have to run as
 // soon as |delay| expires.
 BASE_EXPORT void PostDelayedTaskWithTraits(
     const tracked_objects::Location& from_here,
     const TaskTraits& traits,
-    const Closure& task,
+    Closure task,
     TimeDelta delay);
 
 // Posts |task| with specific |traits| to the TaskScheduler and posts |reply| on
 // the caller's execution context (i.e. same sequence or thread and same
 // TaskTraits if applicable) when |task| completes. Can only be called when
 // SequencedTaskRunnerHandle::IsSet().
 BASE_EXPORT void PostTaskWithTraitsAndReply(
     const tracked_objects::Location& from_here,
     const TaskTraits& traits,
     Closure task,
@@ skipping 36 matching lines @@
 // CreateSequencedTaskRunnerWithTraits(). Only use this if you rely on a thread-
 // affine API (it might be safer to assume thread-affinity when dealing with
 // under-documented third-party APIs, e.g. other OS') or share data across tasks
 // using thread-local storage.
 BASE_EXPORT scoped_refptr<SingleThreadTaskRunner>
 CreateSingleThreadTaskRunnerWithTraits(const TaskTraits& traits);
 
 }  // namespace base
 
 #endif  // BASE_TASK_SCHEDULER_POST_TASK_H_