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- // Copyright 2018 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_OBSERVER_LIST_TYPES_H_
- #define BASE_OBSERVER_LIST_TYPES_H_
- #include "base/base_export.h"
- #include "base/memory/weak_ptr.h"
- namespace base {
- namespace internal {
- class CheckedObserverAdapter;
- }
- // A CheckedObserver serves as a base class for an observer interface designed
- // to be used with base::ObserverList. It helps detect potential use-after-free
- // issues that can occur when observers fail to remove themselves from an
- // observer list upon destruction.
- //
- // A CheckedObserver will CHECK() if an ObserverList iteration is attempted over
- // a destroyed Observer.
- //
- // Note that a CheckedObserver subclass must be deleted on the same thread as
- // the ObserverList(s) it is added to. This is DCHECK()ed via WeakPtr.
- class BASE_EXPORT CheckedObserver {
- public:
- CheckedObserver();
- CheckedObserver(const CheckedObserver&) = delete;
- CheckedObserver& operator=(const CheckedObserver&) = delete;
- virtual ~CheckedObserver();
- // Returns whether |this| is in any ObserverList. Subclasses can CHECK() this
- // in their destructor to obtain a nicer stacktrace.
- bool IsInObserverList() const;
- private:
- friend class internal::CheckedObserverAdapter;
- // Must be mutable to allow ObserverList<const Foo>.
- mutable WeakPtrFactory<CheckedObserver> factory_{this};
- };
- } // namespace base
- #endif // BASE_OBSERVER_LIST_TYPES_H_
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