зеркало из https://github.com/mozilla/gecko-dev.git
104 строки
3.8 KiB
JavaScript
104 строки
3.8 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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"use strict";
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/**
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* Helper class to coordinate Runtime and Page events.
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* Events have to be sent in the following order:
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* - Runtime.executionContextDestroyed
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* - Page.frameNavigated
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* - Runtime.executionContextCreated
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*
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* This class also handles the special case of Pages going from/to the BF cache.
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* When you navigate to a new URL, the previous document may be stored in the BF Cache.
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* All its asynchronous operations are frozen (XHR, timeouts, ...) and a `pagehide` event
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* is fired for this document. We then navigate to the new URL.
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* If the user navigates back to the previous page, the page is resurected from the
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* cache. A `pageshow` event is fired and its asynchronous operations are resumed.
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*
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* When a page is in the BF Cache, we should consider it as frozen and shouldn't try
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* to execute any javascript. So that the ExecutionContext should be considered as
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* being destroyed and the document navigated.
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*/
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var EXPORTED_SYMBOLS = ["ContextObserver"];
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const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
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const {EventEmitter} = ChromeUtils.import("resource://gre/modules/EventEmitter.jsm");
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class ContextObserver {
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constructor(chromeEventHandler) {
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this.chromeEventHandler = chromeEventHandler;
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EventEmitter.decorate(this);
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this.chromeEventHandler.addEventListener("DOMWindowCreated", this,
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{mozSystemGroup: true});
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// Listen for pageshow and pagehide to track pages going in/out to/from the BF Cache
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this.chromeEventHandler.addEventListener("pageshow", this,
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{mozSystemGroup: true});
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this.chromeEventHandler.addEventListener("pagehide", this,
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{mozSystemGroup: true});
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Services.obs.addObserver(this, "inner-window-destroyed");
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}
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destructor() {
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this.chromeEventHandler.removeEventListener("DOMWindowCreated", this,
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{mozSystemGroup: true});
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this.chromeEventHandler.removeEventListener("pageshow", this,
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{mozSystemGroup: true});
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this.chromeEventHandler.removeEventListener("pagehide", this,
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{mozSystemGroup: true});
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Services.obs.removeObserver(this, "inner-window-destroyed");
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}
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handleEvent({type, target, persisted}) {
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const window = target.defaultView;
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if (window.top != this.chromeEventHandler.ownerGlobal) {
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// Ignore iframes for now.
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return;
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}
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const { windowUtils } = window;
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const frameId = windowUtils.outerWindowID;
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const id = windowUtils.currentInnerWindowID;
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switch (type) {
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case "DOMWindowCreated":
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// Do not pass `id` here as that's the new document ID instead of the old one
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// that is destroyed. Instead, pass the frameId and let the listener figure out
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// what ExecutionContext to destroy.
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this.emit("context-destroyed", { frameId });
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this.emit("frame-navigated", { frameId, window });
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this.emit("context-created", { id, window });
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break;
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case "pageshow":
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// `persisted` is true when this is about a page being resurected from BF Cache
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if (!persisted) {
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return;
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}
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// XXX(ochameau) we might have to emit FrameNavigate here to properly handle BF Cache
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// scenario in Page domain events
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this.emit("context-created", { id, window });
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break;
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case "pagehide":
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// `persisted` is true when this is about a page being frozen into BF Cache
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if (!persisted) {
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return;
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}
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this.emit("context-destroyed", { id });
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break;
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}
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}
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// "inner-window-destroyed" observer service listener
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observe(subject, topic, data) {
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const innerWindowID = subject.QueryInterface(Ci.nsISupportsPRUint64).data;
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this.emit("context-destroyed", { id: innerWindowID });
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}
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}
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