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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_LOOP_OBSERVER_H_
#define MEDIA_AUDIO_SCOPED_LOOP_OBSERVER_H_
#include "base/memory/ref_counted.h"
#include "base/message_loop.h"
#include "base/message_loop_proxy.h"
namespace base {
class WaitableEvent;
}
namespace media {
// A common base class for AudioOutputDevice and AudioInputDevice that manages
// a message loop pointer and monitors it for destruction. If the object goes
// out of scope before the message loop, the object will automatically remove
// itself from the message loop's list of destruction observers.
// NOTE: The class that inherits from this class must implement the
// WillDestroyCurrentMessageLoop virtual method from DestructionObserver.
class ScopedLoopObserver
: public base::MessageLoop::DestructionObserver {
public:
explicit ScopedLoopObserver(
const scoped_refptr<base::MessageLoopProxy>& message_loop);
protected:
virtual ~ScopedLoopObserver();
// Accessor to the loop that's used by the derived class.
const scoped_refptr<base::MessageLoopProxy>& message_loop() { return loop_; }
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 message loop's proxy. In case the loop gets destroyed
// before this object goes out of scope, PostTask etc will fail but not crash.
scoped_refptr<base::MessageLoopProxy> loop_;
DISALLOW_COPY_AND_ASSIGN(ScopedLoopObserver);
};
} // namespace media.
#endif // MEDIA_AUDIO_SCOPED_LOOP_OBSERVER_H_
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