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

base/threading/post_task_and_reply_impl.h

 // Copyright (c) 2011 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.
 
 // This file contains the implementation shared by
 // TaskRunner::PostTaskAndReply and WorkerPool::PostTaskAndReply.
 
 #ifndef BASE_THREADING_POST_TASK_AND_REPLY_IMPL_H_
 #define BASE_THREADING_POST_TASK_AND_REPLY_IMPL_H_
 
@@ skipping 16 matching lines @@
   // Posts |task| by calling PostTask(). On completion, |reply| is posted to the
   // sequence or thread that called this. Can only be called when
   // SequencedTaskRunnerHandle::IsSet(). Both |task| and |reply| are guaranteed
   // to be deleted on the sequence or thread that called this.
   bool PostTaskAndReply(const tracked_objects::Location& from_here,
                         Closure task,
                         Closure reply);
 
  private:
   virtual bool PostTask(const tracked_objects::Location& from_here,
-                        const Closure& task) = 0;
+                        Closure task) = 0;
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_THREADING_POST_TASK_AND_REPLY_IMPL_H_