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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
const lazy = {};
ChromeUtils.defineESModuleGetters(lazy, {
EventEmitter: "resource://gre/modules/EventEmitter.sys.mjs",
BrowsingContextListener:
"chrome://remote/content/shared/listeners/BrowsingContextListener.sys.mjs",
});
const OBSERVER_TOPIC_CLOSED = "domwindowclosed";
const OBSERVER_TOPIC_OPENED = "domwindowopened";
/**
* The ChromeWindowListener can be used to listen for notifications
* coming from Chrome windows that get opened or closed.
*
* Example:
* ```
* const listener = new ChromeWindowListener();
* listener.on("opened", onOpened);
* listener.startListening();
*
* const onOpened = (eventName, data = {}) => {
* const { window, why } = data;
* ...
* };
* ```
*
* @fires message
* The ChromeWindowListener emits "opened" and "closed" events,
* with the following object as payload:
* - {ChromeWindow} window
* Chrome window the notification relates to.
*/
export class ChromeWindowListener {
#closingWindows;
#contextListener;
#listening;
/**
* Create a new ChromeWindowListener instance.
*/
constructor() {
lazy.EventEmitter.decorate(this);
// When the `domwindowclosed` notification is sent, the
// containing browsing contexts still exist. We must delay
// emitting the `closed` event until the corresponding
// top-level chrome browsing context has closed as well.
this.#closingWindows = new WeakSet();
this.#contextListener = new lazy.BrowsingContextListener();
this.#listening = false;
}
destroy() {
this.stopListening();
}
observe(subject, topic) {
switch (topic) {
case OBSERVER_TOPIC_OPENED: {
this.emit("opened", { window: subject });
break;
}
case OBSERVER_TOPIC_CLOSED: {
this.#closingWindows.add(subject);
break;
}
}
}
startListening() {
if (this.#listening) {
return;
}
Services.ww.registerNotification(this);
this.#contextListener.on("discarded", this.#onContextDiscarded);
this.#contextListener.startListening();
this.#listening = true;
}
stopListening() {
if (!this.#listening) {
return;
}
this.#contextListener.off("discarded", this.#onContextDiscarded);
this.#contextListener.stopListening();
Services.ww.unregisterNotification(this);
this.#closingWindows = new WeakSet();
this.#listening = false;
}
#onContextDiscarded = (_, data = {}) => {
const { browsingContext } = data;
if (browsingContext.isContent || browsingContext.parent) {
// We only care about top-level chrome browsing contexts
return;
}
const window = browsingContext.topChromeWindow;
if (this.#closingWindows.has(window)) {
this.#closingWindows.delete(window);
this.emit("closed", { window });
}
};
}