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// 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 MEDIA_AUDIO_SCOPED_TASK_RUNNER_OBSERVER_H_
#define MEDIA_AUDIO_SCOPED_TASK_RUNNER_OBSERVER_H_
#include "base/memory/ref_counted.h"
#include "base/message_loop/message_loop.h"
namespace base {
class SingleThreadTaskRunner;
class WaitableEvent;
}
namespace media {
// A common base class for AudioOutputDevice and AudioInputDevice that manages
// a task runner and monitors it for destruction. If the object goes out of
// scope before the task runner, the object will automatically remove itself
// from the task runner's list of destruction observers.
// NOTE: The class that inherits from this class must implement the
// WillDestroyCurrentMessageLoop virtual method from DestructionObserver.
class ScopedTaskRunnerObserver
: public base::MessageLoop::DestructionObserver {
public:
explicit ScopedTaskRunnerObserver(
const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
protected:
virtual ~ScopedTaskRunnerObserver();
// Accessor to the loop that's used by the derived class.
const scoped_refptr<base::SingleThreadTaskRunner>& task_runner() {
return task_runner_;
}
private:
// Call to add or remove ourselves from the list of destruction observers for
// the message loop.
void ObserveLoopDestruction(bool enable, base::WaitableEvent* done);
// A pointer to the task runner. In case it gets destroyed before this object
// goes out of scope, PostTask() etc will fail but not crash.
scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
DISALLOW_COPY_AND_ASSIGN(ScopedTaskRunnerObserver);
};
} // namespace media.
#endif // MEDIA_AUDIO_SCOPED_TASK_RUNNER_OBSERVER_H_
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