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// Copyright 2015 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.
#include "base/macros.h"
namespace web {
class BrowserState;
// Manages the active state associated with a particular BrowserState. Not
// thread safe. Must be used only on the main thread.
class ActiveStateManager {
// Sets the active state of the ActiveStateManager. At most one
// ActiveStateManager can be active at any given time in the app. A
// ActiveStateManager must be made inactive before it is destroyed. It is
// valid to call |SetActive(true)| on an already active ActiveStateManager.
virtual void SetActive(bool active) = 0;
// Returns true if the BrowserState is active.
virtual bool IsActive() = 0;
// Observer that is notified when a ActiveStateManager becomes active,
// inactive or destroyed.
class Observer {
// Called when the ActiveStateManager becomes active.
virtual void OnActive() {}
// Called when the ActiveStateManager becomes inactive.
virtual void OnInactive() {}
// Called just before the ActiveStateManager is destroyed.
virtual void WillBeDestroyed() {}
// Adds an observer for this class. An observer should not be added more
// than once. The caller retains the ownership of the observer object.
virtual void AddObserver(Observer* observer) = 0;
// Removes an observer.
virtual void RemoveObserver(Observer* observer) = 0;
virtual ~ActiveStateManager(){};
} // namespace web