chromium/ios/chrome/browser/tabs/model/tab_parenting_global_observer.h

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef IOS_CHROME_BROWSER_TABS_MODEL_TAB_PARENTING_GLOBAL_OBSERVER_H_
#define IOS_CHROME_BROWSER_TABS_MODEL_TAB_PARENTING_GLOBAL_OBSERVER_H_

#include "base/callback_list.h"
#include "base/no_destructor.h"

namespace web {
class WebState;
}

// Allows clients to observe every tab (i.e., WebState) that is parented.
// NOTE: Should be used only to correspond to //chrome flows that listen for
// the TAB_PARENTED notification from all sources.
class TabParentingGlobalObserver {
 public:
  using OnTabParentedCallback = base::RepeatingCallback<void(web::WebState*)>;

  // Returns the instance of TabParentingGlobalObserver.
  static TabParentingGlobalObserver* GetInstance();

  TabParentingGlobalObserver(const TabParentingGlobalObserver&) = delete;
  TabParentingGlobalObserver& operator=(const TabParentingGlobalObserver&) =
      delete;

  // Registers `cb` to be invoked when a tab is parented.
  base::CallbackListSubscription RegisterCallback(
      const OnTabParentedCallback& cb);

  // Called to notify all registered callbacks that `web_state` was parented.
  void OnTabParented(web::WebState* web_state);

 private:
  friend class base::NoDestructor<TabParentingGlobalObserver>;

  TabParentingGlobalObserver();
  ~TabParentingGlobalObserver();

  base::RepeatingCallbackList<void(web::WebState*)>
      on_tab_parented_callback_list_;
};

#endif  // IOS_CHROME_BROWSER_TABS_MODEL_TAB_PARENTING_GLOBAL_OBSERVER_H_