Migrate base::TaskRunner from Closure to OnceClosure

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,
-                          Closure task);
+                          OnceClosure 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,
-                                 Closure task,
+                                 OnceClosure 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);
+                                  OnceClosure task,
+                                  OnceClosure 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) {
+                                OnceCallback<TaskReturnType()> task,
+                                OnceCallback<void(ReplyArgType)> reply) {
   PostTaskWithTraitsAndReplyWithResult(from_here, TaskTraits(), std::move(task),
                                        std::move(reply));
 }
 
+// Callback version of PostTaskAndReplyWithResult above.
+// Though RepeatingCallback is convertible to OnceCallback, we need this since
+// we can not use template deduction and object conversion at once on the
+// overload resolution.
+// TODO(tzik): Update all callers of the Callback version to use OnceCallback.
+template <typename TaskReturnType, typename ReplyArgType>
+void PostTaskAndReplyWithResult(const tracked_objects::Location& from_here,
+                                Callback<TaskReturnType()> task,
+                                Callback<void(ReplyArgType)> reply) {
+  PostTaskAndReplyWithResult(
+      from_here, static_cast<OnceCallback<TaskReturnType()>>(task),

[gab, 2017/03/29 16:57:35]

std::move(task), std::move(reply)?

[tzik, 2017/03/29 18:17:43]

Ah, right. I forgot to do it. Updated.

+      static_cast<OnceCallback<void(ReplyArgType)>>(reply));

[gab, 2017/03/29 16:57:34]

These casts are effectively doing OnceCallback(task), right? Let's just do that
explicitly?

[tzik, 2017/03/29 18:17:42]

Done.

+}
+
 // Posts |task| with specific |traits| to the TaskScheduler.
 BASE_EXPORT void PostTaskWithTraits(const tracked_objects::Location& from_here,
                                     const TaskTraits& traits,
-                                    Closure task);
+                                    OnceClosure 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,
-    Closure task,
+    OnceClosure 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,
-    Closure reply);
+    OnceClosure task,
+    OnceClosure reply);
 
 // Posts |task| with specific |traits| 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. Can only be called when SequencedTaskRunnerHandle::IsSet().
 template <typename TaskReturnType, typename ReplyArgType>
 void PostTaskWithTraitsAndReplyWithResult(
     const tracked_objects::Location& from_here,
     const TaskTraits& traits,
+    OnceCallback<TaskReturnType()> task,
+    OnceCallback<void(ReplyArgType)> reply) {
+  TaskReturnType* result = new TaskReturnType();
+  return PostTaskWithTraitsAndReply(
+      from_here, traits,
+      BindOnce(&internal::ReturnAsParamAdapter<TaskReturnType>, std::move(task),
+               result),
+      BindOnce(&internal::ReplyAdapter<TaskReturnType, ReplyArgType>,
+               std::move(reply), Owned(result)));
+}
+
+// Callback version of PostTaskWithTraitsAndReplyWithResult above.
+// Though RepeatingCallback is convertible to OnceCallback, we need this since
+// we can not use template deduction and object conversion at once on the
+// overload resolution.
+// TODO(tzik): Update all callers of the Callback version to use OnceCallback.
+template <typename TaskReturnType, typename ReplyArgType>
+void PostTaskWithTraitsAndReplyWithResult(
+    const tracked_objects::Location& from_here,
+    const TaskTraits& traits,
     Callback<TaskReturnType()> task,
     Callback<void(ReplyArgType)> reply) {
-  TaskReturnType* result = new TaskReturnType();
-  return PostTaskWithTraitsAndReply(
-      from_here, traits, Bind(&internal::ReturnAsParamAdapter<TaskReturnType>,
-                              std::move(task), result),
-      Bind(&internal::ReplyAdapter<TaskReturnType, ReplyArgType>,
-           std::move(reply), Owned(result)));
+  PostTaskWithTraitsAndReplyWithResult(
+      from_here, traits,
+      static_cast<OnceCallback<TaskReturnType()>>(std::move(task)),
+      static_cast<OnceCallback<void(ReplyArgType)>>(std::move(reply)));

[gab, 2017/03/29 16:57:35]

ditto

[tzik, 2017/03/29 18:17:43]

Done.

 }
 
 // Returns a TaskRunner whose PostTask invocations result in scheduling tasks
 // using |traits|. Tasks may run in any order and in parallel.
 BASE_EXPORT scoped_refptr<TaskRunner> CreateTaskRunnerWithTraits(
     const TaskTraits& traits);
 
 // Returns a SequencedTaskRunner whose PostTask invocations result in scheduling
 // tasks using |traits|. Tasks run one at a time in posting order.
 BASE_EXPORT scoped_refptr<SequencedTaskRunner>
 CreateSequencedTaskRunnerWithTraits(const TaskTraits& traits);
 
 // Returns a SingleThreadTaskRunner whose PostTask invocations result in
 // scheduling tasks using |traits|. Tasks run on a single thread in posting
 // order.
 //
 // If all you need is to make sure that tasks don't run concurrently (e.g.
 // because they access a data structure which is not thread-safe), use
 // 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_