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

base/message_loop/incoming_task_queue.h

 // Copyright 2013 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_MESSAGE_LOOP_INCOMING_TASK_QUEUE_H_
 #define BASE_MESSAGE_LOOP_INCOMING_TASK_QUEUE_H_
 
 #include "base/base_export.h"
+#include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/pending_task.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/read_write_lock.h"
 #include "base/time/time.h"
 
 namespace base {
 
 class MessageLoop;
 
 namespace internal {
 
 // Implements a queue of tasks posted to the message loop running on the current
 // thread. This class takes care of synchronizing posting tasks from different
 // threads and together with MessageLoop ensures clean shutdown.
 class BASE_EXPORT IncomingTaskQueue
     : public RefCountedThreadSafe<IncomingTaskQueue> {
  public:
   explicit IncomingTaskQueue(MessageLoop* message_loop);
 
   // Appends a task to the incoming queue. Posting of all tasks is routed though
   // AddToIncomingQueue() or TryAddToIncomingQueue() to make sure that posting
   // task is properly synchronized between different threads.
   //
   // Returns true if the task was successfully added to the queue, otherwise
   // returns false. In all cases, the ownership of |task| is transferred to the
   // called method.
   bool AddToIncomingQueue(const tracked_objects::Location& from_here,
-                          const Closure& task,
+                          Closure task,
                           TimeDelta delay,
                           bool nestable);
 
   // Returns true if the queue contains tasks that require higher than default
   // timer resolution. Currently only needed for Windows.
   bool HasHighResolutionTasks();
 
   // Returns true if the message loop is "idle". Provided for testing.
   bool IsIdleForTesting();
 
@@ skipping 56 matching lines @@
   // False until StartScheduling() is called.
   bool is_ready_for_scheduling_;
 
   DISALLOW_COPY_AND_ASSIGN(IncomingTaskQueue);
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_INCOMING_TASK_QUEUE_H_