DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Mercurial (e03e0c60462c)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364
/* 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
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

this.EXPORTED_SYMBOLS = ["ExtensionUtils"];

const Ci = Components.interfaces;
const Cc = Components.classes;
const Cu = Components.utils;
const Cr = Components.results;

const INTEGER = /^[1-9]\d*$/;

Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://gre/modules/XPCOMUtils.jsm");

XPCOMUtils.defineLazyModuleGetter(this, "AddonManager",
                                  "resource://gre/modules/AddonManager.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "AppConstants",
                                  "resource://gre/modules/AppConstants.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "ConsoleAPI",
                                  "resource://gre/modules/Console.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "ExtensionManagement",
                                  "resource://gre/modules/ExtensionManagement.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "IndexedDB",
                                  "resource://gre/modules/IndexedDB.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "LanguageDetector",
                                  "resource:///modules/translation/LanguageDetector.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Locale",
                                  "resource://gre/modules/Locale.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "MessageChannel",
                                  "resource://gre/modules/MessageChannel.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
                                  "resource://gre/modules/NetUtil.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Preferences",
                                  "resource://gre/modules/Preferences.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Schemas",
                                  "resource://gre/modules/Schemas.jsm");

XPCOMUtils.defineLazyServiceGetter(this, "styleSheetService",
                                   "@mozilla.org/content/style-sheet-service;1",
                                   "nsIStyleSheetService");

/* globals IDBKeyRange */

function getConsole() {
  return new ConsoleAPI({
    maxLogLevelPref: "extensions.webextensions.log.level",
    prefix: "WebExtensions",
  });
}

XPCOMUtils.defineLazyGetter(this, "console", getConsole);

let nextId = 0;
XPCOMUtils.defineLazyGetter(this, "uniqueProcessID", () => Services.appinfo.uniqueProcessID);

function getUniqueId() {
  return `${nextId++}-${uniqueProcessID}`;
}

// The list of properties that themes are allowed to contain.
XPCOMUtils.defineLazyGetter(this, "gAllowedThemeProperties", () => {
  Cu.import("resource://gre/modules/ExtensionParent.jsm");
  let propertiesInBaseManifest = ExtensionParent.baseManifestProperties;

  // The properties found in the base manifest contain all of the properties that
  // themes are allowed to have. However, the list also contains several properties
  // that aren't allowed, so we need to filter them out first before the list can
  // be used to validate themes.
  return propertiesInBaseManifest.filter(prop => {
    const propertiesToRemove = ["background", "content_scripts", "permissions"];
    return !propertiesToRemove.includes(prop);
  });
});

/**
 * Validates a theme to ensure it only contains static resources.
 *
 * @param {Array<string>} manifestProperties The list of top-level keys found in the
 *    the extension's manifest.
 * @returns {Array<string>} A list of invalid properties or an empty list
 *    if none are found.
 */
function validateThemeManifest(manifestProperties) {
  let invalidProps = [];
  for (let propName of manifestProperties) {
    if (propName != "theme" && !gAllowedThemeProperties.includes(propName)) {
      invalidProps.push(propName);
    }
  }
  return invalidProps;
}

let StartupCache = {
  DB_NAME: "ExtensionStartupCache",

  SCHEMA_VERSION: 1,

  STORE_NAMES: Object.freeze(["locales", "manifests", "schemas"]),

  dbPromise: null,

  cacheInvalidated: 0,

  initDB(db) {
    for (let name of StartupCache.STORE_NAMES) {
      try {
        db.deleteObjectStore(name);
      } catch (e) {
        // Don't worry if the store doesn't already exist.
      }
      db.createObjectStore(name);
    }
  },

  clearAddonData(id) {
    let range = IDBKeyRange.bound([id], [id, "\uFFFF"]);

    return Promise.all([
      this.locales.delete(range),
      this.manifests.delete(range),
    ]).catch(e => {
      // Ignore the error. It happens when we try to flush the add-on
      // data after the AddonManager has flushed the entire startup cache.
    });
  },

  async reallyOpen(invalidate = false) {
    if (this.dbPromise) {
      let db = await this.dbPromise;
      db.close();
    }

    if (invalidate) {
      this.cacheInvalidated = ExtensionManagement.cacheInvalidated;

      if (Services.appinfo.processType === Services.appinfo.PROCESS_TYPE_DEFAULT) {
        IndexedDB.deleteDatabase(this.DB_NAME, {storage: "persistent"});
      }
    }

    return IndexedDB.open(this.DB_NAME,
                          {storage: "persistent", version: this.SCHEMA_VERSION},
                          db => this.initDB(db));
  },

  async open() {
    if (ExtensionManagement.cacheInvalidated > this.cacheInvalidated) {
      this.dbPromise = this.reallyOpen(true);
    } else if (!this.dbPromise) {
      this.dbPromise = this.reallyOpen();
    }

    return this.dbPromise;
  },

  observe(subject, topic, data) {
    if (topic === "startupcache-invalidate") {
      this.dbPromise = this.reallyOpen(true).catch(e => {});
    }
  },
};

Services.obs.addObserver(StartupCache, "startupcache-invalidate", false);

class CacheStore {
  constructor(storeName) {
    this.storeName = storeName;
  }

  async get(key, createFunc) {
    let db;
    let value;
    try {
      db = await StartupCache.open();

      value = await db.objectStore(this.storeName)
                      .get(key);
    } catch (e) {
      Cu.reportError(e);

      return createFunc(key);
    }

    if (value === undefined) {
      value = await createFunc(key);

      db.objectStore(this.storeName, "readwrite")
        .put(value, key);
    }

    return value;
  }

  async delete(key) {
    let db = await StartupCache.open();

    return db.objectStore(this.storeName, "readwrite").delete(key);
  }
}

for (let name of StartupCache.STORE_NAMES) {
  StartupCache[name] = new CacheStore(name);
}

/**
 * An Error subclass for which complete error messages are always passed
 * to extensions, rather than being interpreted as an unknown error.
 */
class ExtensionError extends Error {}

function filterStack(error) {
  return String(error.stack).replace(/(^.*(Task\.jsm|Promise-backend\.js).*\n)+/gm, "<Promise Chain>\n");
}

// Run a function and report exceptions.
function runSafeSyncWithoutClone(f, ...args) {
  try {
    return f(...args);
  } catch (e) {
    dump(`Extension error: ${e} ${e.fileName} ${e.lineNumber}\n[[Exception stack\n${filterStack(e)}Current stack\n${filterStack(Error())}]]\n`);
    Cu.reportError(e);
  }
}

// Run a function and report exceptions.
function runSafeWithoutClone(f, ...args) {
  if (typeof(f) != "function") {
    dump(`Extension error: expected function\n${filterStack(Error())}`);
    return;
  }

  Promise.resolve().then(() => {
    runSafeSyncWithoutClone(f, ...args);
  });
}

// Run a function, cloning arguments into context.cloneScope, and
// report exceptions. |f| is expected to be in context.cloneScope.
function runSafeSync(context, f, ...args) {
  if (context.unloaded) {
    Cu.reportError("runSafeSync called after context unloaded");
    return;
  }

  try {
    args = Cu.cloneInto(args, context.cloneScope);
  } catch (e) {
    Cu.reportError(e);
    dump(`runSafe failure: cloning into ${context.cloneScope}: ${e}\n\n${filterStack(Error())}`);
  }
  return runSafeSyncWithoutClone(f, ...args);
}

// Run a function, cloning arguments into context.cloneScope, and
// report exceptions. |f| is expected to be in context.cloneScope.
function runSafe(context, f, ...args) {
  try {
    args = Cu.cloneInto(args, context.cloneScope);
  } catch (e) {
    Cu.reportError(e);
    dump(`runSafe failure: cloning into ${context.cloneScope}: ${e}\n\n${filterStack(Error())}`);
  }
  if (context.unloaded) {
    dump(`runSafe failure: context is already unloaded ${filterStack(new Error())}\n`);
    return undefined;
  }
  return runSafeWithoutClone(f, ...args);
}

function getInnerWindowID(window) {
  return window.QueryInterface(Ci.nsIInterfaceRequestor)
    .getInterface(Ci.nsIDOMWindowUtils)
    .currentInnerWindowID;
}

// Return true if the given value is an instance of the given
// native type.
function instanceOf(value, type) {
  return {}.toString.call(value) == `[object ${type}]`;
}

// Extend the object |obj| with the property descriptors of each object in
// |args|.
function extend(obj, ...args) {
  for (let arg of args) {
    let props = [...Object.getOwnPropertyNames(arg),
                 ...Object.getOwnPropertySymbols(arg)];
    for (let prop of props) {
      let descriptor = Object.getOwnPropertyDescriptor(arg, prop);
      Object.defineProperty(obj, prop, descriptor);
    }
  }

  return obj;
}

/**
 * Similar to a WeakMap, but creates a new key with the given
 * constructor if one is not present.
 */
class DefaultWeakMap extends WeakMap {
  constructor(defaultConstructor, init) {
    super(init);
    this.defaultConstructor = defaultConstructor;
  }

  get(key) {
    if (!this.has(key)) {
      this.set(key, this.defaultConstructor(key));
    }
    return super.get(key);
  }
}

class DefaultMap extends Map {
  constructor(defaultConstructor, init) {
    super(init);
    this.defaultConstructor = defaultConstructor;
  }

  get(key) {
    if (!this.has(key)) {
      this.set(key, this.defaultConstructor(key));
    }
    return super.get(key);
  }
}

class SpreadArgs extends Array {
  constructor(args) {
    super();
    this.push(...args);
  }
}

// Manages icon details for toolbar buttons in the |pageAction| and
// |browserAction| APIs.
let IconDetails = {
  // Normalizes the various acceptable input formats into an object
  // with icon size as key and icon URL as value.
  //
  // If a context is specified (function is called from an extension):
  // Throws an error if an invalid icon size was provided or the
  // extension is not allowed to load the specified resources.
  //
  // If no context is specified, instead of throwing an error, this
  // function simply logs a warning message.
  normalize(details, extension, context = null) {
    let result = {};

    try {
      if (details.imageData) {
        let imageData = details.imageData;

        if (typeof imageData == "string") {
          imageData = {"19": imageData};
        }

        for (let size of Object.keys(imageData)) {
          if (!INTEGER.test(size)) {
            throw new ExtensionError(`Invalid icon size ${size}, must be an integer`);
          }
          result[size] = imageData[size];
        }
      }

      if (details.path) {
        let path = details.path;
        if (typeof path != "object") {
          path = {"19": path};
        }

        let baseURI = context ? context.uri : extension.baseURI;

        for (let size of Object.keys(path)) {
          if (!INTEGER.test(size)) {
            throw new ExtensionError(`Invalid icon size ${size}, must be an integer`);
          }

          let url = baseURI.resolve(path[size]);

          // The Chrome documentation specifies these parameters as
          // relative paths. We currently accept absolute URLs as well,
          // which means we need to check that the extension is allowed
          // to load them. This will throw an error if it's not allowed.
          try {
            Services.scriptSecurityManager.checkLoadURIStrWithPrincipal(
              extension.principal, url,
              Services.scriptSecurityManager.DISALLOW_SCRIPT);
          } catch (e) {
            throw new ExtensionError(`Illegal URL ${url}`);
          }

          result[size] = url;
        }
      }
    } catch (e) {
      // Function is called from extension code, delegate error.
      if (context) {
        throw e;
      }
      // If there's no context, it's because we're handling this
      // as a manifest directive. Log a warning rather than
      // raising an error.
      extension.manifestError(`Invalid icon data: ${e}`);
    }

    return result;
  },

  // Returns the appropriate icon URL for the given icons object and the
  // screen resolution of the given window.
  getPreferredIcon(icons, extension = null, size = 16) {
    const DEFAULT = "chrome://browser/content/extension.svg";

    let bestSize = null;
    if (icons[size]) {
      bestSize = size;
    } else if (icons[2 * size]) {
      bestSize = 2 * size;
    } else {
      let sizes = Object.keys(icons)
                        .map(key => parseInt(key, 10))
                        .sort((a, b) => a - b);

      bestSize = sizes.find(candidate => candidate > size) || sizes.pop();
    }

    if (bestSize) {
      return {size: bestSize, icon: icons[bestSize]};
    }

    return {size, icon: DEFAULT};
  },

  convertImageURLToDataURL(imageURL, contentWindow, browserWindow, size = 18) {
    return new Promise((resolve, reject) => {
      let image = new contentWindow.Image();
      image.onload = function() {
        let canvas = contentWindow.document.createElement("canvas");
        let ctx = canvas.getContext("2d");
        let dSize = size * browserWindow.devicePixelRatio;

        // Scales the image while maintaing width to height ratio.
        // If the width and height differ, the image is centered using the
        // smaller of the two dimensions.
        let dWidth, dHeight, dx, dy;
        if (this.width > this.height) {
          dWidth = dSize;
          dHeight = image.height * (dSize / image.width);
          dx = 0;
          dy = (dSize - dHeight) / 2;
        } else {
          dWidth = image.width * (dSize / image.height);
          dHeight = dSize;
          dx = (dSize - dWidth) / 2;
          dy = 0;
        }

        ctx.drawImage(this, 0, 0, this.width, this.height, dx, dy, dWidth, dHeight);
        resolve(canvas.toDataURL("image/png"));
      };
      image.onerror = reject;
      image.src = imageURL;
    });
  },

  // These URLs should already be properly escaped, but make doubly sure CSS
  // string escape characters are escaped here, since they could lead to a
  // sandbox break.
  escapeUrl(url) {
    return url.replace(/[\\\s"]/g, encodeURIComponent);
  },
};

const LISTENERS = Symbol("listeners");

class EventEmitter {
  constructor() {
    this[LISTENERS] = new Map();
  }

  /**
   * Adds the given function as a listener for the given event.
   *
   * The listener function may optionally return a Promise which
   * resolves when it has completed all operations which event
   * dispatchers may need to block on.
   *
   * @param {string} event
   *       The name of the event to listen for.
   * @param {function(string, ...any)} listener
   *        The listener to call when events are emitted.
   */
  on(event, listener) {
    if (!this[LISTENERS].has(event)) {
      this[LISTENERS].set(event, new Set());
    }

    this[LISTENERS].get(event).add(listener);
  }

  /**
   * Removes the given function as a listener for the given event.
   *
   * @param {string} event
   *       The name of the event to stop listening for.
   * @param {function(string, ...any)} listener
   *        The listener function to remove.
   */
  off(event, listener) {
    if (this[LISTENERS].has(event)) {
      let set = this[LISTENERS].get(event);

      set.delete(listener);
      if (!set.size) {
        this[LISTENERS].delete(event);
      }
    }
  }

  /**
   * Triggers all listeners for the given event, and returns a promise
   * which resolves when all listeners have been called, and any
   * promises they have returned have likewise resolved.
   *
   * @param {string} event
   *       The name of the event to emit.
   * @param {any} args
   *        Arbitrary arguments to pass to the listener functions, after
   *        the event name.
   * @returns {Promise}
   */
  emit(event, ...args) {
    let listeners = this[LISTENERS].get(event) || new Set();

    let promises = Array.from(listeners, listener => {
      return runSafeSyncWithoutClone(listener, event, ...args);
    });

    return Promise.all(promises);
  }
}

function LocaleData(data) {
  this.defaultLocale = data.defaultLocale;
  this.selectedLocale = data.selectedLocale;
  this.locales = data.locales || new Map();
  this.warnedMissingKeys = new Set();

  // Map(locale-name -> Map(message-key -> localized-string))
  //
  // Contains a key for each loaded locale, each of which is a
  // Map of message keys to their localized strings.
  this.messages = data.messages || new Map();

  if (data.builtinMessages) {
    this.messages.set(this.BUILTIN, data.builtinMessages);
  }
}


LocaleData.prototype = {
  // Representation of the object to send to content processes. This
  // should include anything the content process might need.
  serialize() {
    return {
      defaultLocale: this.defaultLocale,
      selectedLocale: this.selectedLocale,
      messages: this.messages,
      locales: this.locales,
    };
  },

  BUILTIN: "@@BUILTIN_MESSAGES",

  has(locale) {
    return this.messages.has(locale);
  },

  // https://developer.chrome.com/extensions/i18n
  localizeMessage(message, substitutions = [], options = {}) {
    let defaultOptions = {
      locale: this.selectedLocale,
      defaultValue: "",
      cloneScope: null,
    };

    options = Object.assign(defaultOptions, options);

    let locales = new Set([this.BUILTIN, options.locale, this.defaultLocale]
                          .filter(locale => this.messages.has(locale)));

    // Message names are case-insensitive, so normalize them to lower-case.
    message = message.toLowerCase();
    for (let locale of locales) {
      let messages = this.messages.get(locale);
      if (messages.has(message)) {
        let str = messages.get(message);

        if (!Array.isArray(substitutions)) {
          substitutions = [substitutions];
        }

        let replacer = (matched, index, dollarSigns) => {
          if (index) {
            // This is not quite Chrome-compatible. Chrome consumes any number
            // of digits following the $, but only accepts 9 substitutions. We
            // accept any number of substitutions.
            index = parseInt(index, 10) - 1;
            return index in substitutions ? substitutions[index] : "";
          }
          // For any series of contiguous `$`s, the first is dropped, and
          // the rest remain in the output string.
          return dollarSigns;
        };
        return str.replace(/\$(?:([1-9]\d*)|(\$+))/g, replacer);
      }
    }

    // Check for certain pre-defined messages.
    if (message == "@@ui_locale") {
      return this.uiLocale;
    } else if (message.startsWith("@@bidi_")) {
      let registry = Cc["@mozilla.org/chrome/chrome-registry;1"].getService(Ci.nsIXULChromeRegistry);
      let rtl = registry.isLocaleRTL("global");

      if (message == "@@bidi_dir") {
        return rtl ? "rtl" : "ltr";
      } else if (message == "@@bidi_reversed_dir") {
        return rtl ? "ltr" : "rtl";
      } else if (message == "@@bidi_start_edge") {
        return rtl ? "right" : "left";
      } else if (message == "@@bidi_end_edge") {
        return rtl ? "left" : "right";
      }
    }

    if (!this.warnedMissingKeys.has(message)) {
      let error = `Unknown localization message ${message}`;
      if (options.cloneScope) {
        error = new options.cloneScope.Error(error);
      }
      Cu.reportError(error);
      this.warnedMissingKeys.add(message);
    }
    return options.defaultValue;
  },

  // Localize a string, replacing all |__MSG_(.*)__| tokens with the
  // matching string from the current locale, as determined by
  // |this.selectedLocale|.
  //
  // This may not be called before calling either |initLocale| or
  // |initAllLocales|.
  localize(str, locale = this.selectedLocale) {
    if (!str) {
      return str;
    }

    return str.replace(/__MSG_([A-Za-z0-9@_]+?)__/g, (matched, message) => {
      return this.localizeMessage(message, [], {locale, defaultValue: matched});
    });
  },

  // Validates the contents of a locale JSON file, normalizes the
  // messages into a Map of message key -> localized string pairs.
  addLocale(locale, messages, extension) {
    let result = new Map();

    // Chrome does not document the semantics of its localization
    // system very well. It handles replacements by pre-processing
    // messages, replacing |$[a-zA-Z0-9@_]+$| tokens with the value of their
    // replacements. Later, it processes the resulting string for
    // |$[0-9]| replacements.
    //
    // Again, it does not document this, but it accepts any number
    // of sequential |$|s, and replaces them with that number minus
    // 1. It also accepts |$| followed by any number of sequential
    // digits, but refuses to process a localized string which
    // provides more than 9 substitutions.
    if (!instanceOf(messages, "Object")) {
      extension.packagingError(`Invalid locale data for ${locale}`);
      return result;
    }

    for (let key of Object.keys(messages)) {
      let msg = messages[key];

      if (!instanceOf(msg, "Object") || typeof(msg.message) != "string") {
        extension.packagingError(`Invalid locale message data for ${locale}, message ${JSON.stringify(key)}`);
        continue;
      }

      // Substitutions are case-insensitive, so normalize all of their names
      // to lower-case.
      let placeholders = new Map();
      if (instanceOf(msg.placeholders, "Object")) {
        for (let key of Object.keys(msg.placeholders)) {
          placeholders.set(key.toLowerCase(), msg.placeholders[key]);
        }
      }

      let replacer = (match, name) => {
        let replacement = placeholders.get(name.toLowerCase());
        if (instanceOf(replacement, "Object") && "content" in replacement) {
          return replacement.content;
        }
        return "";
      };

      let value = msg.message.replace(/\$([A-Za-z0-9@_]+)\$/g, replacer);

      // Message names are also case-insensitive, so normalize them to lower-case.
      result.set(key.toLowerCase(), value);
    }

    this.messages.set(locale, result);
    return result;
  },

  get acceptLanguages() {
    let result = Preferences.get("intl.accept_languages", "", Ci.nsIPrefLocalizedString);
    return result.split(/\s*,\s*/g);
  },


  get uiLocale() {
    // Return the browser locale, but convert it to a Chrome-style
    // locale code.
    return Locale.getLocale().replace(/-/g, "_");
  },
};

// This is a generic class for managing event listeners. Example usage:
//
// new SingletonEventManager(context, "api.subAPI", fire => {
//   let listener = (...) => {
//     // Fire any listeners registered with addListener.
//     fire.async(arg1, arg2);
//   };
//   // Register the listener.
//   SomehowRegisterListener(listener);
//   return () => {
//     // Return a way to unregister the listener.
//     SomehowUnregisterListener(listener);
//   };
// }).api()
//
// The result is an object with addListener, removeListener, and
// hasListener methods. |context| is an add-on scope (either an
// ExtensionContext in the chrome process or ExtensionContext in a
// content process). |name| is for debugging. |register| is a function
// to register the listener. |register| should return an
// unregister function that will unregister the listener.
function SingletonEventManager(context, name, register) {
  this.context = context;
  this.name = name;
  this.register = register;
  this.unregister = new Map();
}

SingletonEventManager.prototype = {
  addListener(callback, ...args) {
    if (this.unregister.has(callback)) {
      return;
    }

    let shouldFire = () => {
      if (this.context.unloaded) {
        dump(`${this.name} event fired after context unloaded.\n`);
      } else if (!this.context.active) {
        dump(`${this.name} event fired while context is inactive.\n`);
      } else if (this.unregister.has(callback)) {
        return true;
      }
      return false;
    };

    let fire = {
      sync: (...args) => {
        if (shouldFire()) {
          return this.context.runSafe(callback, ...args);
        }
      },
      async: (...args) => {
        return Promise.resolve().then(() => {
          if (shouldFire()) {
            return this.context.runSafe(callback, ...args);
          }
        });
      },
      raw: (...args) => {
        if (!shouldFire()) {
          throw new Error("Called raw() on unloaded/inactive context");
        }
        return callback(...args);
      },
      asyncWithoutClone: (...args) => {
        return Promise.resolve().then(() => {
          if (shouldFire()) {
            return this.context.runSafeWithoutClone(callback, ...args);
          }
        });
      },
    };


    let unregister = this.register(fire, ...args);
    this.unregister.set(callback, unregister);
    this.context.callOnClose(this);
  },

  removeListener(callback) {
    if (!this.unregister.has(callback)) {
      return;
    }

    let unregister = this.unregister.get(callback);
    this.unregister.delete(callback);
    try {
      unregister();
    } catch (e) {
      Cu.reportError(e);
    }
    if (this.unregister.size == 0) {
      this.context.forgetOnClose(this);
    }
  },

  hasListener(callback) {
    return this.unregister.has(callback);
  },

  revoke() {
    for (let callback of this.unregister.keys()) {
      this.removeListener(callback);
    }
  },

  close() {
    this.revoke();
  },

  api() {
    return {
      addListener: (...args) => this.addListener(...args),
      removeListener: (...args) => this.removeListener(...args),
      hasListener: (...args) => this.hasListener(...args),
      [Schemas.REVOKE]: () => this.revoke(),
    };
  },
};

// Simple API for event listeners where events never fire.
function ignoreEvent(context, name) {
  return {
    addListener: function(callback) {
      let id = context.extension.id;
      let frame = Components.stack.caller;
      let msg = `In add-on ${id}, attempting to use listener "${name}", which is unimplemented.`;
      let scriptError = Cc["@mozilla.org/scripterror;1"]
        .createInstance(Ci.nsIScriptError);
      scriptError.init(msg, frame.filename, null, frame.lineNumber,
                       frame.columnNumber, Ci.nsIScriptError.warningFlag,
                       "content javascript");
      let consoleService = Cc["@mozilla.org/consoleservice;1"]
        .getService(Ci.nsIConsoleService);
      consoleService.logMessage(scriptError);
    },
    removeListener: function(callback) {},
    hasListener: function(callback) {},
  };
}

// Copy an API object from |source| into the scope |dest|.
function injectAPI(source, dest) {
  for (let prop in source) {
    // Skip names prefixed with '_'.
    if (prop[0] == "_") {
      continue;
    }

    let desc = Object.getOwnPropertyDescriptor(source, prop);
    if (typeof(desc.value) == "function") {
      Cu.exportFunction(desc.value, dest, {defineAs: prop});
    } else if (typeof(desc.value) == "object") {
      let obj = Cu.createObjectIn(dest, {defineAs: prop});
      injectAPI(desc.value, obj);
    } else {
      Object.defineProperty(dest, prop, desc);
    }
  }
}

/**
 * A set with a limited number of slots, which flushes older entries as
 * newer ones are added.
 */
class LimitedSet extends Set {
  constructor(limit, iterable = undefined) {
    super(iterable);
    this.limit = limit;
  }

  truncate(limit) {
    for (let item of this) {
      if (this.size <= limit) {
        break;
      }
      this.delete(item);
    }
  }

  add(item) {
    if (!this.has(item) && this.size >= this.limit) {
      this.truncate(this.limit - 1);
    }
    super.add(item);
  }
}

/**
 * Returns a Promise which resolves when the given document's DOM has
 * fully loaded.
 *
 * @param {Document} doc The document to await the load of.
 * @returns {Promise<Document>}
 */
function promiseDocumentReady(doc) {
  if (doc.readyState == "interactive" || doc.readyState == "complete") {
    return Promise.resolve(doc);
  }

  return new Promise(resolve => {
    doc.addEventListener("DOMContentLoaded", function onReady(event) {
      if (event.target === event.currentTarget) {
        doc.removeEventListener("DOMContentLoaded", onReady, true);
        resolve(doc);
      }
    }, true);
  });
}

/**
 * Returns a Promise which resolves when the given document is fully
 * loaded.
 *
 * @param {Document} doc The document to await the load of.
 * @returns {Promise<Document>}
 */
function promiseDocumentLoaded(doc) {
  if (doc.readyState == "complete") {
    return Promise.resolve(doc);
  }

  return new Promise(resolve => {
    doc.defaultView.addEventListener("load", function(event) {
      resolve(doc);
    }, {once: true});
  });
}

/**
 * Returns a Promise which resolves when the given event is dispatched to the
 * given element.
 *
 * @param {Element} element
 *        The element on which to listen.
 * @param {string} eventName
 *        The event to listen for.
 * @param {boolean} [useCapture = true]
 *        If true, listen for the even in the capturing rather than
 *        bubbling phase.
 * @param {Event} [test]
 *        An optional test function which, when called with the
 *        observer's subject and data, should return true if this is the
 *        expected event, false otherwise.
 * @returns {Promise<Event>}
 */
function promiseEvent(element, eventName, useCapture = true, test = event => true) {
  return new Promise(resolve => {
    function listener(event) {
      if (test(event)) {
        element.removeEventListener(eventName, listener, useCapture);
        resolve(event);
      }
    }
    element.addEventListener(eventName, listener, useCapture);
  });
}

/**
 * Returns a Promise which resolves the given observer topic has been
 * observed.
 *
 * @param {string} topic
 *        The topic to observe.
 * @param {function(nsISupports, string)} [test]
 *        An optional test function which, when called with the
 *        observer's subject and data, should return true if this is the
 *        expected notification, false otherwise.
 * @returns {Promise<object>}
 */
function promiseObserved(topic, test = () => true) {
  return new Promise(resolve => {
    let observer = (subject, topic, data) => {
      if (test(subject, data)) {
        Services.obs.removeObserver(observer, topic);
        resolve({subject, data});
      }
    };
    Services.obs.addObserver(observer, topic, false);
  });
}

function getMessageManager(target) {
  if (target instanceof Ci.nsIFrameLoaderOwner) {
    return target.QueryInterface(Ci.nsIFrameLoaderOwner).frameLoader.messageManager;
  }
  return target.QueryInterface(Ci.nsIMessageSender);
}

function flushJarCache(jarPath) {
  Services.obs.notifyObservers(null, "flush-cache-entry", jarPath);
}

function PlatformInfo() {
  return Object.freeze({
    os: (function() {
      let os = AppConstants.platform;
      if (os == "macosx") {
        os = "mac";
      }
      return os;
    })(),
    arch: (function() {
      let abi = Services.appinfo.XPCOMABI;
      let [arch] = abi.split("-");
      if (arch == "x86") {
        arch = "x86-32";
      } else if (arch == "x86_64") {
        arch = "x86-64";
      }
      return arch;
    })(),
  });
}

function detectLanguage(text) {
  return LanguageDetector.detectLanguage(text).then(result => ({
    isReliable: result.confident,
    languages: result.languages.map(lang => {
      return {
        language: lang.languageCode,
        percentage: lang.percent,
      };
    }),
  }));
}

/**
 * Convert any of several different representations of a date/time to a Date object.
 * Accepts several formats:
 * a Date object, an ISO8601 string, or a number of milliseconds since the epoch as
 * either a number or a string.
 *
 * @param {Date|string|number} date
 *      The date to convert.
 * @returns {Date}
 *      A Date object
 */
function normalizeTime(date) {
  // Of all the formats we accept the "number of milliseconds since the epoch as a string"
  // is an outlier, everything else can just be passed directly to the Date constructor.
  return new Date((typeof date == "string" && /^\d+$/.test(date))
                        ? parseInt(date, 10) : date);
}

const stylesheetMap = new DefaultMap(url => {
  let uri = NetUtil.newURI(url);
  return styleSheetService.preloadSheet(uri, styleSheetService.AGENT_SHEET);
});

/**
 * Defines a lazy getter for the given property on the given object. The
 * first time the property is accessed, the return value of the getter
 * is defined on the current `this` object with the given property name.
 * Importantly, this means that a lazy getter defined on an object
 * prototype will be invoked separately for each object instance that
 * it's accessed on.
 *
 * @param {object} object
 *        The prototype object on which to define the getter.
 * @param {string|Symbol} prop
 *        The property name for which to define the getter.
 * @param {function} getter
 *        The function to call in order to generate the final property
 *        value.
 */
function defineLazyGetter(object, prop, getter) {
  let redefine = (obj, value) => {
    Object.defineProperty(obj, prop, {
      enumerable: true,
      configurable: true,
      writable: true,
      value,
    });
    return value;
  };

  Object.defineProperty(object, prop, {
    enumerable: true,
    configurable: true,

    get() {
      return redefine(this, getter.call(this));
    },

    set(value) {
      redefine(this, value);
    },
  });
}

function findPathInObject(obj, path, printErrors = true) {
  let parent;
  for (let elt of path.split(".")) {
    if (!obj || !(elt in obj)) {
      if (printErrors) {
        Cu.reportError(`WebExtension API ${path} not found (it may be unimplemented by Firefox).`);
      }
      return null;
    }

    parent = obj;
    obj = obj[elt];
  }

  if (typeof obj === "function") {
    return obj.bind(parent);
  }
  return obj;
}

/**
 * Acts as a proxy for a message manager or message manager owner, and
 * tracks docShell swaps so that messages are always sent to the same
 * receiver, even if it is moved to a different <browser>.
 *
 * @param {nsIMessageSender|Element} target
 *        The target message manager on which to send messages, or the
 *        <browser> element which owns it.
 */
class MessageManagerProxy {
  constructor(target) {
    this.listeners = new DefaultMap(() => new Map());

    if (target instanceof Ci.nsIMessageSender) {
      Object.defineProperty(this, "messageManager", {
        value: target,
        configurable: true,
        writable: true,
      });
    } else {
      this.addListeners(target);
    }
  }

  /**
   * Disposes of the proxy object, removes event listeners, and drops
   * all references to the underlying message manager.
   *
   * Must be called before the last reference to the proxy is dropped,
   * unless the underlying message manager or <browser> is also being
   * destroyed.
   */
  dispose() {
    if (this.eventTarget) {
      this.removeListeners(this.eventTarget);
      this.eventTarget = null;
    } else {
      this.messageManager = null;
    }
  }

  /**
   * Returns true if the given target is the same as, or owns, the given
   * message manager.
   *
   * @param {nsIMessageSender|MessageManagerProxy|Element} target
   *        The message manager, MessageManagerProxy, or <browser>
   *        element agaisnt which to match.
   * @param {nsIMessageSender} messageManager
   *        The message manager against which to match `target`.
   *
   * @returns {boolean}
   *        True if `messageManager` is the same object as `target`, or
   *        `target` is a MessageManagerProxy or <browser> element that
   *        is tied to it.
   */
  static matches(target, messageManager) {
    return target === messageManager || target.messageManager === messageManager;
  }

  /**
   * @property {nsIMessageSender|null} messageManager
   *        The message manager that is currently being proxied. This
   *        may change during the life of the proxy object, so should
   *        not be stored elsewhere.
   */
  get messageManager() {
    return this.eventTarget && this.eventTarget.messageManager;
  }

  /**
   * Sends a message on the proxied message manager.
   *
   * @param {array} args
   *        Arguments to be passed verbatim to the underlying
   *        sendAsyncMessage method.
   * @returns {undefined}
   */
  sendAsyncMessage(...args) {
    if (this.messageManager) {
      return this.messageManager.sendAsyncMessage(...args);
    }
    /* globals uneval */
    Cu.reportError(`Cannot send message: Other side disconnected: ${uneval(args)}`);
  }

  get isDisconnected() {
    return !this.messageManager;
  }

  /**
   * Adds a message listener to the current message manager, and
   * transfers it to the new message manager after a docShell swap.
   *
   * @param {string} message
   *        The name of the message to listen for.
   * @param {nsIMessageListener} listener
   *        The listener to add.
   * @param {boolean} [listenWhenClosed = false]
   *        If true, the listener will receive messages which were sent
   *        after the remote side of the listener began closing.
   */
  addMessageListener(message, listener, listenWhenClosed = false) {
    this.messageManager.addMessageListener(message, listener, listenWhenClosed);
    this.listeners.get(message).set(listener, listenWhenClosed);
  }

  /**
   * Adds a message listener from the current message manager.
   *
   * @param {string} message
   *        The name of the message to stop listening for.
   * @param {nsIMessageListener} listener
   *        The listener to remove.
   */
  removeMessageListener(message, listener) {
    this.messageManager.removeMessageListener(message, listener);

    let listeners = this.listeners.get(message);
    listeners.delete(listener);
    if (!listeners.size) {
      this.listeners.delete(message);
    }
  }

  /**
   * @private
   * Iterates over all of the currently registered message listeners.
   */
  * iterListeners() {
    for (let [message, listeners] of this.listeners) {
      for (let [listener, listenWhenClosed] of listeners) {
        yield {message, listener, listenWhenClosed};
      }
    }
  }

  /**
   * @private
   * Adds docShell swap listeners to the message manager owner.
   *
   * @param {Element} target
   *        The target element.
   */
  addListeners(target) {
    target.addEventListener("SwapDocShells", this);

    for (let {message, listener, listenWhenClosed} of this.iterListeners()) {
      target.addMessageListener(message, listener, listenWhenClosed);
    }

    this.eventTarget = target;
  }

  /**
   * @private
   * Removes docShell swap listeners to the message manager owner.
   *
   * @param {Element} target
   *        The target element.
   */
  removeListeners(target) {
    target.removeEventListener("SwapDocShells", this);

    for (let {message, listener} of this.iterListeners()) {
      target.removeMessageListener(message, listener);
    }
  }

  handleEvent(event) {
    if (event.type == "SwapDocShells") {
      this.removeListeners(this.eventTarget);
      this.addListeners(event.detail);
    }
  }
}

this.ExtensionUtils = {
  defineLazyGetter,
  detectLanguage,
  extend,
  findPathInObject,
  flushJarCache,
  getConsole,
  getInnerWindowID,
  getMessageManager,
  getUniqueId,
  ignoreEvent,
  injectAPI,
  instanceOf,
  normalizeTime,
  promiseDocumentLoaded,
  promiseDocumentReady,
  promiseEvent,
  promiseObserved,
  runSafe,
  runSafeSync,
  runSafeSyncWithoutClone,
  runSafeWithoutClone,
  stylesheetMap,
  validateThemeManifest,
  DefaultMap,
  DefaultWeakMap,
  EventEmitter,
  ExtensionError,
  IconDetails,
  LimitedSet,
  LocaleData,
  MessageManagerProxy,
  SingletonEventManager,
  SpreadArgs,
  StartupCache,
};

XPCOMUtils.defineLazyGetter(this.ExtensionUtils, "PlatformInfo", PlatformInfo);