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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef BASE_MESSAGE_LOOP_MESSAGE_LOOP_TASK_RUNNER_H_
      6 #define BASE_MESSAGE_LOOP_MESSAGE_LOOP_TASK_RUNNER_H_
      7 
      8 #include "base/base_export.h"
      9 #include "base/callback.h"
     10 #include "base/macros.h"
     11 #include "base/memory/ref_counted.h"
     12 #include "base/pending_task.h"
     13 #include "base/single_thread_task_runner.h"
     14 #include "base/synchronization/lock.h"
     15 #include "base/threading/platform_thread.h"
     16 
     17 namespace base {
     18 namespace internal {
     19 
     20 class IncomingTaskQueue;
     21 
     22 // A stock implementation of SingleThreadTaskRunner that is created and managed
     23 // by a MessageLoop. For now a MessageLoopTaskRunner can only be created as
     24 // part of a MessageLoop.
     25 class BASE_EXPORT MessageLoopTaskRunner : public SingleThreadTaskRunner {
     26  public:
     27   explicit MessageLoopTaskRunner(
     28       scoped_refptr<IncomingTaskQueue> incoming_queue);
     29 
     30   // Initialize this message loop task runner on the current thread.
     31   void BindToCurrentThread();
     32 
     33   // SingleThreadTaskRunner implementation
     34   bool PostDelayedTask(const tracked_objects::Location& from_here,
     35                        OnceClosure task,
     36                        base::TimeDelta delay) override;
     37   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
     38                                   OnceClosure task,
     39                                   base::TimeDelta delay) override;
     40   bool RunsTasksOnCurrentThread() const override;
     41 
     42  private:
     43   friend class RefCountedThreadSafe<MessageLoopTaskRunner>;
     44   ~MessageLoopTaskRunner() override;
     45 
     46   // The incoming queue receiving all posted tasks.
     47   scoped_refptr<IncomingTaskQueue> incoming_queue_;
     48 
     49   // ID of the thread |this| was created on.  Could be accessed on multiple
     50   // threads, protected by |valid_thread_id_lock_|.
     51   PlatformThreadId valid_thread_id_;
     52   mutable Lock valid_thread_id_lock_;
     53 
     54   DISALLOW_COPY_AND_ASSIGN(MessageLoopTaskRunner);
     55 };
     56 
     57 }  // namespace internal
     58 }  // namespace base
     59 
     60 #endif  // BASE_MESSAGE_LOOP_MESSAGE_LOOP_TASK_RUNNER_H_
     61