471 lines
17 KiB
JavaScript
471 lines
17 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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const EXPORTED_SYMBOLS = [
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"BackgroundPageThumbs",
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];
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const DEFAULT_CAPTURE_TIMEOUT = 30000; // ms
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const DESTROY_BROWSER_TIMEOUT = 60000; // ms
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const FRAME_SCRIPT_URL = "chrome://global/content/backgroundPageThumbsContent.js";
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const TELEMETRY_HISTOGRAM_ID_PREFIX = "FX_THUMBNAILS_BG_";
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const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
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const HTML_NS = "http://www.w3.org/1999/xhtml";
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const { classes: Cc, interfaces: Ci, utils: Cu } = Components;
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Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
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Cu.import("resource://gre/modules/PageThumbs.jsm");
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Cu.import("resource://gre/modules/Services.jsm");
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Cu.import("resource://gre/modules/Task.jsm");
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// possible FX_THUMBNAILS_BG_CAPTURE_DONE_REASON_2 telemetry values
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const TEL_CAPTURE_DONE_OK = 0;
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const TEL_CAPTURE_DONE_TIMEOUT = 1;
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// 2 and 3 were used when we had special handling for private-browsing.
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const TEL_CAPTURE_DONE_CRASHED = 4;
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const TEL_CAPTURE_DONE_BAD_URI = 5;
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// These are looked up on the global as properties below.
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XPCOMUtils.defineConstant(this, "TEL_CAPTURE_DONE_OK", TEL_CAPTURE_DONE_OK);
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XPCOMUtils.defineConstant(this, "TEL_CAPTURE_DONE_TIMEOUT", TEL_CAPTURE_DONE_TIMEOUT);
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XPCOMUtils.defineConstant(this, "TEL_CAPTURE_DONE_CRASHED", TEL_CAPTURE_DONE_CRASHED);
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XPCOMUtils.defineConstant(this, "TEL_CAPTURE_DONE_BAD_URI", TEL_CAPTURE_DONE_BAD_URI);
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const global = this;
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// contains base64 version of a placeholder thumbnail
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#include blankthumb.inc
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const BackgroundPageThumbs = {
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/**
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* Asynchronously captures a thumbnail of the given URL.
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*
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* The page is loaded anonymously, and plug-ins are disabled.
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*
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* @param url The URL to capture.
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* @param options An optional object that configures the capture. Its
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* properties are the following, and all are optional:
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* @opt onDone A function that will be asynchronously called when the
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* capture is complete or times out. It's called as
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* onDone(url),
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* where `url` is the captured URL.
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* @opt timeout The capture will time out after this many milliseconds have
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* elapsed after the capture has progressed to the head of
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* the queue and started. Defaults to 30000 (30 seconds).
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*/
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capture: function (url, options={}) {
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if (!PageThumbs._prefEnabled()) {
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if (options.onDone)
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schedule(() => options.onDone(url));
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return;
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}
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this._captureQueue = this._captureQueue || [];
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this._capturesByURL = this._capturesByURL || new Map();
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tel("QUEUE_SIZE_ON_CAPTURE", this._captureQueue.length);
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// We want to avoid duplicate captures for the same URL. If there is an
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// existing one, we just add the callback to that one and we are done.
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let existing = this._capturesByURL.get(url);
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if (existing) {
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if (options.onDone)
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existing.doneCallbacks.push(options.onDone);
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// The queue is already being processed, so nothing else to do...
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return;
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}
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let cap = new Capture(url, this._onCaptureOrTimeout.bind(this), options);
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this._captureQueue.push(cap);
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this._capturesByURL.set(url, cap);
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this._processCaptureQueue();
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},
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/**
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* Asynchronously captures a thumbnail of the given URL if one does not
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* already exist. Otherwise does nothing.
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*
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* @param url The URL to capture.
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* @param options An optional object that configures the capture. See
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* capture() for description.
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* @return {Promise} A Promise that resolves when this task completes
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*/
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captureIfMissing: Task.async(function* (url, options={}) {
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// The fileExistsForURL call is an optimization, potentially but unlikely
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// incorrect, and no big deal when it is. After the capture is done, we
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// atomically test whether the file exists before writing it.
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let exists = yield PageThumbsStorage.fileExistsForURL(url);
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if (exists) {
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if (options.onDone) {
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options.onDone(url);
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}
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return url;
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}
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let thumbPromise = new Promise((resolve, reject) => {
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function observe(subject, topic, data) { // jshint ignore:line
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if (data === url) {
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switch (topic) {
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case "page-thumbnail:create":
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resolve();
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break;
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case "page-thumbnail:error":
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reject(new Error("page-thumbnail:error"));
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break;
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}
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Services.obs.removeObserver(observe, "page-thumbnail:create");
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Services.obs.removeObserver(observe, "page-thumbnail:error");
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}
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}
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Services.obs.addObserver(observe, "page-thumbnail:create", false);
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Services.obs.addObserver(observe, "page-thumbnail:error", false);
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});
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try {
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this.capture(url, options);
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yield thumbPromise;
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} catch (err) {
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if (options.onDone) {
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options.onDone(url);
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}
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throw err;
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}
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return url;
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}),
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/**
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* Ensures that initialization of the thumbnail browser's parent window has
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* begun.
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*
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* @return True if the parent window is completely initialized and can be
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* used, and false if initialization has started but not completed.
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*/
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_ensureParentWindowReady: function () {
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if (this._parentWin)
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// Already fully initialized.
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return true;
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if (this._startedParentWinInit)
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// Already started initializing.
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return false;
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this._startedParentWinInit = true;
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// Create an html:iframe, stick it in the parent document, and
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// use it to host the browser. about:blank will not have the system
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// principal, so it can't host, but a document with a chrome URI will.
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let hostWindow = Services.appShell.hiddenDOMWindow;
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let iframe = hostWindow.document.createElementNS(HTML_NS, "iframe");
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iframe.setAttribute("src", "chrome://global/content/mozilla.xhtml");
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let onLoad = function onLoadFn() {
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iframe.removeEventListener("load", onLoad, true);
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this._parentWin = iframe.contentWindow;
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this._processCaptureQueue();
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}.bind(this);
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iframe.addEventListener("load", onLoad, true);
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hostWindow.document.documentElement.appendChild(iframe);
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this._hostIframe = iframe;
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return false;
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},
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/**
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* Destroys the service. Queued and pending captures will never complete, and
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* their consumer callbacks will never be called.
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*/
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_destroy: function () {
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if (this._captureQueue)
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this._captureQueue.forEach(cap => cap.destroy());
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this._destroyBrowser();
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if (this._hostIframe)
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this._hostIframe.remove();
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delete this._captureQueue;
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delete this._hostIframe;
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delete this._startedParentWinInit;
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delete this._parentWin;
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},
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/**
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* Creates the thumbnail browser if it doesn't already exist.
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*/
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_ensureBrowser: function () {
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if (this._thumbBrowser)
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return;
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let browser = this._parentWin.document.createElementNS(XUL_NS, "browser");
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browser.setAttribute("type", "content");
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browser.setAttribute("disableglobalhistory", "true");
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if (Services.prefs.getPrefType("browser.tabs.remote") == Services.prefs.PREF_BOOL &&
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Services.prefs.getBoolPref("browser.tabs.remote")) {
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browser.setAttribute("remote", "true");
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}
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// Size the browser. Make its aspect ratio the same as the canvases' that
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// the thumbnails are drawn into; the canvases' aspect ratio is the same as
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// the screen's, so use that. Aim for a size in the ballpark of 1024x768.
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let [swidth, sheight] = [{}, {}];
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Cc["@mozilla.org/gfx/screenmanager;1"].
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getService(Ci.nsIScreenManager).
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primaryScreen.
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GetRectDisplayPix({}, {}, swidth, sheight);
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let bwidth = Math.min(1024, swidth.value);
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// Setting the width and height attributes doesn't work -- the resulting
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// thumbnails are blank and transparent -- but setting the style does.
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browser.style.width = bwidth + "px";
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browser.style.height = (bwidth * sheight.value / swidth.value) + "px";
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this._parentWin.document.documentElement.appendChild(browser);
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// an event that is sent if the remote process crashes - no need to remove
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// it as we want it to be there as long as the browser itself lives.
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browser.addEventListener("oop-browser-crashed", () => {
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Cu.reportError("BackgroundThumbnails remote process crashed - recovering");
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this._destroyBrowser();
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let curCapture = this._captureQueue.length ? this._captureQueue[0] : null;
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// we could retry the pending capture, but it's possible the crash
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// was due directly to it, so trying again might just crash again.
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// We could keep a flag to indicate if it previously crashed, but
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// "resetting" the capture requires more work - so for now, we just
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// discard it.
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if (curCapture && curCapture.pending) {
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// Continue queue processing by calling curCapture._done(). Do it after
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// this crashed listener returns, though. A new browser will be created
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// immediately (on the same stack as the _done call stack) if there are
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// any more queued-up captures, and that seems to mess up the new
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// browser's message manager if it happens on the same stack as the
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// listener. Trying to send a message to the manager in that case
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// throws NS_ERROR_NOT_INITIALIZED.
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Services.tm.currentThread.dispatch(() => {
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curCapture._done(null, TEL_CAPTURE_DONE_CRASHED);
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}, Ci.nsIEventTarget.DISPATCH_NORMAL);
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}
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// else: we must have been idle and not currently doing a capture (eg,
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// maybe a GC or similar crashed) - so there's no need to attempt a
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// queue restart - the next capture request will set everything up.
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});
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browser.messageManager.loadFrameScript(FRAME_SCRIPT_URL, false);
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this._thumbBrowser = browser;
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},
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_destroyBrowser: function () {
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if (!this._thumbBrowser)
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return;
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this._thumbBrowser.remove();
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delete this._thumbBrowser;
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},
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/**
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* Starts the next capture if the queue is not empty and the service is fully
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* initialized.
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*/
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_processCaptureQueue: function () {
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if (!this._captureQueue.length ||
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this._captureQueue[0].pending ||
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!this._ensureParentWindowReady())
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return;
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// Ready to start the first capture in the queue.
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this._ensureBrowser();
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this._captureQueue[0].start(this._thumbBrowser.messageManager);
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if (this._destroyBrowserTimer) {
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this._destroyBrowserTimer.cancel();
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delete this._destroyBrowserTimer;
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}
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},
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/**
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* Called when the current capture completes or fails (eg, times out, remote
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* process crashes.)
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*/
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_onCaptureOrTimeout: function (capture) {
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// Since timeouts start as an item is being processed, only the first
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// item in the queue can be passed to this method.
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if (capture !== this._captureQueue[0])
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throw new Error("The capture should be at the head of the queue.");
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this._captureQueue.shift();
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this._capturesByURL.delete(capture.url);
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if (capture.doneReason != TEL_CAPTURE_DONE_OK) {
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Services.obs.notifyObservers(null, "page-thumbnail:error", capture.url);
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}
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// Start the destroy-browser timer *before* processing the capture queue.
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let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
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timer.initWithCallback(this._destroyBrowser.bind(this),
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this._destroyBrowserTimeout,
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Ci.nsITimer.TYPE_ONE_SHOT);
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this._destroyBrowserTimer = timer;
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this._processCaptureQueue();
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},
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_destroyBrowserTimeout: DESTROY_BROWSER_TIMEOUT,
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};
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Object.defineProperty(this, "BackgroundPageThumbs", {
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value: BackgroundPageThumbs,
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enumerable: true,
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writable: false
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});
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/**
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* Represents a single capture request in the capture queue.
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*
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* @param url The URL to capture.
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* @param captureCallback A function you want called when the capture
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* completes.
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* @param options The capture options.
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*/
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function Capture(url, captureCallback, options) {
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this.url = url;
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this.captureCallback = captureCallback;
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this.options = options;
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this.id = Capture.nextID++;
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this.creationDate = new Date();
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this.doneCallbacks = [];
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this.doneReason;
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if (options.onDone)
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this.doneCallbacks.push(options.onDone);
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}
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Capture.prototype = {
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get pending() {
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return !!this._msgMan;
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},
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/**
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* Sends a message to the content script to start the capture.
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*
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* @param messageManager The nsIMessageSender of the thumbnail browser.
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*/
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start: function (messageManager) {
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this.startDate = new Date();
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tel("CAPTURE_QUEUE_TIME_MS", this.startDate - this.creationDate);
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// timeout timer
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let timeout;
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if (this.options && typeof(this.options.timeout) == "number") {
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timeout = this.options.timeout;
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} else {
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timeout = DEFAULT_CAPTURE_TIMEOUT;
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}
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this._timeoutTimer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
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this._timeoutTimer.initWithCallback(this, timeout,
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Ci.nsITimer.TYPE_ONE_SHOT);
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// didCapture registration
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this._msgMan = messageManager;
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this._msgMan.sendAsyncMessage("BackgroundPageThumbs:capture",
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{ id: this.id, url: this.url });
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this._msgMan.addMessageListener("BackgroundPageThumbs:didCapture", this);
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},
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/**
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* The only intended external use of this method is by the service when it's
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* uninitializing and doing things like destroying the thumbnail browser. In
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* that case the consumer's completion callback will never be called.
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*/
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destroy: function () {
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// This method may be called for captures that haven't started yet, so
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// guard against not yet having _timeoutTimer, _msgMan etc properties...
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if (this._timeoutTimer) {
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this._timeoutTimer.cancel();
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delete this._timeoutTimer;
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}
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if (this._msgMan) {
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this._msgMan.removeMessageListener("BackgroundPageThumbs:didCapture",
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this);
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delete this._msgMan;
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}
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delete this.captureCallback;
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delete this.doneCallbacks;
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delete this.options;
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},
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// Called when the didCapture message is received.
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receiveMessage: function (msg) {
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if (msg.data.imageData)
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tel("CAPTURE_SERVICE_TIME_MS", new Date() - this.startDate);
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// A different timed-out capture may have finally successfully completed, so
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// discard messages that aren't meant for this capture.
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if (msg.data.id != this.id)
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return;
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if (msg.data.failReason) {
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let reason = global["TEL_CAPTURE_DONE_" + msg.data.failReason];
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this._done(null, reason);
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return;
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}
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this._done(msg.data, TEL_CAPTURE_DONE_OK);
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},
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// Called when the timeout timer fires.
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notify: function () {
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this._done(null, TEL_CAPTURE_DONE_TIMEOUT);
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},
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_done: function (data, reason) {
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// Note that _done will be called only once, by either receiveMessage or
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// notify, since it calls destroy here, which cancels the timeout timer and
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// removes the didCapture message listener.
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let { captureCallback, doneCallbacks, options } = this;
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this.destroy();
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this.doneReason = reason;
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if (typeof(reason) != "number") {
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throw new Error("A done reason must be given.");
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}
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tel("CAPTURE_DONE_REASON_2", reason);
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if (data && data.telemetry) {
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// Telemetry is currently disabled in the content process (bug 680508).
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for (let id in data.telemetry) {
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tel(id, data.telemetry[id]);
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}
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}
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let done = () => {
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captureCallback(this);
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for (let callback of doneCallbacks) {
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try {
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callback.call(options, this.url);
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}
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catch (err) {
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Cu.reportError(err);
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}
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}
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};
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if (!data) {
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// If this background attempt failed, cause a placeholder file to be saved, so
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// that gets loaded instead of attempting again (and again).
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PageThumbs._store(this.url, this.url, atob(BLANKTHUMB), true)
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.then(done, done);
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return;
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}
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PageThumbs._store(this.url, data.finalURL, data.imageData, true)
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.then(done, done);
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},
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};
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Capture.nextID = 0;
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/**
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* Adds a value to one of this module's telemetry histograms.
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*
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* @param histogramID This is prefixed with this module's ID.
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* @param value The value to add.
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*/
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function tel(histogramID, value) {
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let id = TELEMETRY_HISTOGRAM_ID_PREFIX + histogramID;
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Services.telemetry.getHistogramById(id).add(value);
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}
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function schedule(callback) {
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Services.tm.mainThread.dispatch(callback, Ci.nsIThread.DISPATCH_NORMAL);
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}
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