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

base/threading/worker_pool.h

 // Copyright (c) 2012 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_THREADING_WORKER_POOL_H_
 #define BASE_THREADING_WORKER_POOL_H_
 
 #include "base/base_export.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
@@ skipping 14 matching lines @@
 // inside the pool must be extremely careful about other objects they access
 // (MessageLoops, Singletons, etc). During shutdown these object may no longer
 // exist.
 class BASE_EXPORT WorkerPool {
  public:
   // This function posts |task| to run on a worker thread.  |task_is_slow|
   // should be used for tasks that will take a long time to execute.  Returns
   // false if |task| could not be posted to a worker thread.  Regardless of
   // return value, ownership of |task| is transferred to the worker pool.
   static bool PostTask(const tracked_objects::Location& from_here,
-                       const base::Closure& task, bool task_is_slow);
+                       Closure task,
+                       bool task_is_slow);
 
   // Just like TaskRunner::PostTaskAndReply, except the destination
   // for |task| is a worker thread and you can specify |task_is_slow| just
   // like you can for PostTask above.
   static bool PostTaskAndReply(const tracked_objects::Location& from_here,
                                Closure task,
                                Closure reply,
                                bool task_is_slow);
 
   // Return true if the current thread is one that this WorkerPool runs tasks
   // on.  (Note that if the Windows worker pool is used without going through
   // this WorkerPool interface, RunsTasksOnCurrentThread would return false on
   // those threads.)
   static bool RunsTasksOnCurrentThread();
 
   // Get a TaskRunner wrapper which posts to the WorkerPool using the given
   // |task_is_slow| behavior.
   static const scoped_refptr<TaskRunner>& GetTaskRunner(bool task_is_slow);
 };
 
 }  // namespace base
 
 #endif  // BASE_THREADING_WORKER_POOL_H_