Add Basilisk

1 files changed, 1559 insertions, 0 deletions

diff --git a/application/basilisk/components/downloads/DownloadsCommon.jsm b/application/basilisk/components/downloads/DownloadsCommon.jsm
new file mode 100644
index 000000000..674902096
--- /dev/null
+++ b/application/basilisk/components/downloads/DownloadsCommon.jsm
@@ -0,0 +1,1559 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80 filetype=javascript: */
+/* 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 = [
+  "DownloadsCommon",
+];
+
+/**
+ * Handles the Downloads panel shared methods and data access.
+ *
+ * This file includes the following constructors and global objects:
+ *
+ * DownloadsCommon
+ * This object is exposed directly to the consumers of this JavaScript module,
+ * and provides shared methods for all the instances of the user interface.
+ *
+ * DownloadsData
+ * Retrieves the list of past and completed downloads from the underlying
+ * Downloads API data, and provides asynchronous notifications allowing
+ * to build a consistent view of the available data.
+ *
+ * DownloadsIndicatorData
+ * This object registers itself with DownloadsData as a view, and transforms the
+ * notifications it receives into overall status data, that is then broadcast to
+ * the registered download status indicators.
+ */
+
+////////////////////////////////////////////////////////////////////////////////
+//// Globals
+
+const { classes: Cc, interfaces: Ci, utils: Cu, results: Cr } = Components;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+
+XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
+                                  "resource://gre/modules/NetUtil.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "PluralForm",
+                                  "resource://gre/modules/PluralForm.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "Downloads",
+                                  "resource://gre/modules/Downloads.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "DownloadUIHelper",
+                                  "resource://gre/modules/DownloadUIHelper.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "DownloadUtils",
+                                  "resource://gre/modules/DownloadUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
+                                  "resource://gre/modules/FileUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "OS",
+                                  "resource://gre/modules/osfile.jsm")
+XPCOMUtils.defineLazyModuleGetter(this, "PlacesUtils",
+                                  "resource://gre/modules/PlacesUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "PrivateBrowsingUtils",
+                                  "resource://gre/modules/PrivateBrowsingUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "RecentWindow",
+                                  "resource:///modules/RecentWindow.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "Promise",
+                                  "resource://gre/modules/Promise.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "Task",
+                                  "resource://gre/modules/Task.jsm");
+
+XPCOMUtils.defineLazyGetter(this, "DownloadsLogger", () => {
+  let { ConsoleAPI } = Cu.import("resource://gre/modules/Console.jsm", {});
+  let consoleOptions = {
+    maxLogLevelPref: "browser.download.loglevel",
+    prefix: "Downloads"
+  };
+  return new ConsoleAPI(consoleOptions);
+});
+
+const nsIDM = Ci.nsIDownloadManager;
+
+const kDownloadsStringBundleUrl =
+  "chrome://browser/locale/downloads/downloads.properties";
+
+const kDownloadsStringsRequiringFormatting = {
+  sizeWithUnits: true,
+  shortTimeLeftSeconds: true,
+  shortTimeLeftMinutes: true,
+  shortTimeLeftHours: true,
+  shortTimeLeftDays: true,
+  statusSeparator: true,
+  statusSeparatorBeforeNumber: true,
+  fileExecutableSecurityWarning: true
+};
+
+const kDownloadsStringsRequiringPluralForm = {
+  otherDownloads3: true
+};
+
+const kPartialDownloadSuffix = ".part";
+
+const kPrefBranch = Services.prefs.getBranch("browser.download.");
+
+var PrefObserver = {
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver,
+                                         Ci.nsISupportsWeakReference]),
+  getPref(name) {
+    try {
+      switch (typeof this.prefs[name]) {
+        case "boolean":
+          return kPrefBranch.getBoolPref(name);
+      }
+    } catch (ex) { }
+    return this.prefs[name];
+  },
+  observe(aSubject, aTopic, aData) {
+    if (this.prefs.hasOwnProperty(aData)) {
+      delete this[aData];
+      return this[aData] = this.getPref(aData);
+    }
+  },
+  register(prefs) {
+    this.prefs = prefs;
+    kPrefBranch.addObserver("", this, true);
+    for (let key in prefs) {
+      let name = key;
+      XPCOMUtils.defineLazyGetter(this, name, function () {
+        return PrefObserver.getPref(name);
+      });
+    }
+  },
+};
+
+PrefObserver.register({
+  // prefName: defaultValue
+  animateNotifications: true,
+  showPanelDropmarker: true,
+});
+
+
+////////////////////////////////////////////////////////////////////////////////
+//// DownloadsCommon
+
+/**
+ * This object is exposed directly to the consumers of this JavaScript module,
+ * and provides shared methods for all the instances of the user interface.
+ */
+this.DownloadsCommon = {
+  ATTENTION_NONE: "",
+  ATTENTION_SUCCESS: "success",
+  ATTENTION_WARNING: "warning",
+  ATTENTION_SEVERE: "severe",
+
+  /**
+   * Returns an object whose keys are the string names from the downloads string
+   * bundle, and whose values are either the translated strings or functions
+   * returning formatted strings.
+   */
+  get strings() {
+    let strings = {};
+    let sb = Services.strings.createBundle(kDownloadsStringBundleUrl);
+    let enumerator = sb.getSimpleEnumeration();
+    while (enumerator.hasMoreElements()) {
+      let string = enumerator.getNext().QueryInterface(Ci.nsIPropertyElement);
+      let stringName = string.key;
+      if (stringName in kDownloadsStringsRequiringFormatting) {
+        strings[stringName] = function () {
+          // Convert "arguments" to a real array before calling into XPCOM.
+          return sb.formatStringFromName(stringName,
+                                         Array.slice(arguments, 0),
+                                         arguments.length);
+        };
+      } else if (stringName in kDownloadsStringsRequiringPluralForm) {
+        strings[stringName] = function (aCount) {
+          // Convert "arguments" to a real array before calling into XPCOM.
+          let formattedString = sb.formatStringFromName(stringName,
+                                         Array.slice(arguments, 0),
+                                         arguments.length);
+          return PluralForm.get(aCount, formattedString);
+        };
+      } else {
+        strings[stringName] = string.value;
+      }
+    }
+    delete this.strings;
+    return this.strings = strings;
+  },
+
+  /**
+   * Generates a very short string representing the given time left.
+   *
+   * @param aSeconds
+   *        Value to be formatted.  It represents the number of seconds, it must
+   *        be positive but does not need to be an integer.
+   *
+   * @return Formatted string, for example "30s" or "2h".  The returned value is
+   *         maximum three characters long, at least in English.
+   */
+  formatTimeLeft(aSeconds) {
+    // Decide what text to show for the time
+    let seconds = Math.round(aSeconds);
+    if (!seconds) {
+      return "";
+    } else if (seconds <= 30) {
+      return DownloadsCommon.strings["shortTimeLeftSeconds"](seconds);
+    }
+    let minutes = Math.round(aSeconds / 60);
+    if (minutes < 60) {
+      return DownloadsCommon.strings["shortTimeLeftMinutes"](minutes);
+    }
+    let hours = Math.round(minutes / 60);
+    if (hours < 48) { // two days
+      return DownloadsCommon.strings["shortTimeLeftHours"](hours);
+    }
+    let days = Math.round(hours / 24);
+    return DownloadsCommon.strings["shortTimeLeftDays"](Math.min(days, 99));
+  },
+
+  /**
+   * Indicates whether we should show visual notification on the indicator
+   * when a download event is triggered.
+   */
+  get animateNotifications() {
+    return PrefObserver.animateNotifications;
+  },
+
+  /**
+   * Indicates whether we should show the dropmarker in the Downloads Panel.
+   */
+  get showPanelDropmarker() {
+    return PrefObserver.showPanelDropmarker;
+  },
+
+  /**
+   * Get access to one of the DownloadsData or PrivateDownloadsData objects,
+   * depending on the privacy status of the window in question.
+   *
+   * @param aWindow
+   *        The browser window which owns the download button.
+   */
+  getData(aWindow) {
+    if (PrivateBrowsingUtils.isContentWindowPrivate(aWindow)) {
+      return PrivateDownloadsData;
+    } else {
+      return DownloadsData;
+    }
+  },
+
+  /**
+   * Initializes the Downloads back-end and starts receiving events for both the
+   * private and non-private downloads data objects.
+   */
+  initializeAllDataLinks() {
+    DownloadsData.initializeDataLink();
+    PrivateDownloadsData.initializeDataLink();
+  },
+
+  /**
+   * Get access to one of the DownloadsIndicatorData or
+   * PrivateDownloadsIndicatorData objects, depending on the privacy status of
+   * the window in question.
+   */
+  getIndicatorData(aWindow) {
+    if (PrivateBrowsingUtils.isContentWindowPrivate(aWindow)) {
+      return PrivateDownloadsIndicatorData;
+    } else {
+      return DownloadsIndicatorData;
+    }
+  },
+
+  /**
+   * Returns a reference to the DownloadsSummaryData singleton - creating one
+   * in the process if one hasn't been instantiated yet.
+   *
+   * @param aWindow
+   *        The browser window which owns the download button.
+   * @param aNumToExclude
+   *        The number of items on the top of the downloads list to exclude
+   *        from the summary.
+   */
+  getSummary(aWindow, aNumToExclude) {
+    if (PrivateBrowsingUtils.isContentWindowPrivate(aWindow)) {
+      if (this._privateSummary) {
+        return this._privateSummary;
+      }
+      return this._privateSummary = new DownloadsSummaryData(true, aNumToExclude);
+    } else {
+      if (this._summary) {
+        return this._summary;
+      }
+      return this._summary = new DownloadsSummaryData(false, aNumToExclude);
+    }
+  },
+  _summary: null,
+  _privateSummary: null,
+
+  /**
+   * Returns the legacy state integer value for the provided Download object.
+   */
+  stateOfDownload(download) {
+    // Collapse state using the correct priority.
+    if (!download.stopped) {
+      return nsIDM.DOWNLOAD_DOWNLOADING;
+    }
+    if (download.succeeded) {
+      return nsIDM.DOWNLOAD_FINISHED;
+    }
+    if (download.error) {
+      if (download.error.becauseBlockedByParentalControls) {
+        return nsIDM.DOWNLOAD_BLOCKED_PARENTAL;
+      }
+      if (download.error.becauseBlockedByReputationCheck) {
+        return nsIDM.DOWNLOAD_DIRTY;
+      }
+      return nsIDM.DOWNLOAD_FAILED;
+    }
+    if (download.canceled) {
+      if (download.hasPartialData) {
+        return nsIDM.DOWNLOAD_PAUSED;
+      }
+      return nsIDM.DOWNLOAD_CANCELED;
+    }
+    return nsIDM.DOWNLOAD_NOTSTARTED;
+  },
+
+  /**
+   * Helper function required because the Downloads Panel and the Downloads View
+   * don't share the controller yet.
+   */
+  removeAndFinalizeDownload(download) {
+    Downloads.getList(Downloads.ALL)
+             .then(list => list.remove(download))
+             .then(() => download.finalize(true))
+             .catch(Cu.reportError);
+  },
+
+  /**
+   * Given an iterable collection of Download objects, generates and returns
+   * statistics about that collection.
+   *
+   * @param downloads An iterable collection of Download objects.
+   *
+   * @return Object whose properties are the generated statistics. Currently,
+   *         we return the following properties:
+   *
+   *         numActive       : The total number of downloads.
+   *         numPaused       : The total number of paused downloads.
+   *         numDownloading  : The total number of downloads being downloaded.
+   *         totalSize       : The total size of all downloads once completed.
+   *         totalTransferred: The total amount of transferred data for these
+   *                           downloads.
+   *         slowestSpeed    : The slowest download rate.
+   *         rawTimeLeft     : The estimated time left for the downloads to
+   *                           complete.
+   *         percentComplete : The percentage of bytes successfully downloaded.
+   */
+  summarizeDownloads(downloads) {
+    let summary = {
+      numActive: 0,
+      numPaused: 0,
+      numDownloading: 0,
+      totalSize: 0,
+      totalTransferred: 0,
+      // slowestSpeed is Infinity so that we can use Math.min to
+      // find the slowest speed. We'll set this to 0 afterwards if
+      // it's still at Infinity by the time we're done iterating all
+      // download.
+      slowestSpeed: Infinity,
+      rawTimeLeft: -1,
+      percentComplete: -1
+    }
+
+    for (let download of downloads) {
+      summary.numActive++;
+
+      if (!download.stopped) {
+        summary.numDownloading++;
+        if (download.hasProgress && download.speed > 0) {
+          let sizeLeft = download.totalBytes - download.currentBytes;
+          summary.rawTimeLeft = Math.max(summary.rawTimeLeft,
+                                         sizeLeft / download.speed);
+          summary.slowestSpeed = Math.min(summary.slowestSpeed,
+                                          download.speed);
+        }
+      } else if (download.canceled && download.hasPartialData) {
+        summary.numPaused++;
+      }
+
+      // Only add to total values if we actually know the download size.
+      if (download.succeeded) {
+        summary.totalSize += download.target.size;
+        summary.totalTransferred += download.target.size;
+      } else if (download.hasProgress) {
+        summary.totalSize += download.totalBytes;
+        summary.totalTransferred += download.currentBytes;
+      }
+    }
+
+    if (summary.totalSize != 0) {
+      summary.percentComplete = (summary.totalTransferred /
+                                 summary.totalSize) * 100;
+    }
+
+    if (summary.slowestSpeed == Infinity) {
+      summary.slowestSpeed = 0;
+    }
+
+    return summary;
+  },
+
+  /**
+   * If necessary, smooths the estimated number of seconds remaining for one
+   * or more downloads to complete.
+   *
+   * @param aSeconds
+   *        Current raw estimate on number of seconds left for one or more
+   *        downloads. This is a floating point value to help get sub-second
+   *        accuracy for current and future estimates.
+   */
+  smoothSeconds(aSeconds, aLastSeconds) {
+    // We apply an algorithm similar to the DownloadUtils.getTimeLeft function,
+    // though tailored to a single time estimation for all downloads.  We never
+    // apply something if the new value is less than half the previous value.
+    let shouldApplySmoothing = aLastSeconds >= 0 &&
+                               aSeconds > aLastSeconds / 2;
+    if (shouldApplySmoothing) {
+      // Apply hysteresis to favor downward over upward swings.  Trust only 30%
+      // of the new value if lower, and 10% if higher (exponential smoothing).
+      let diff = aSeconds - aLastSeconds;
+      aSeconds = aLastSeconds + (diff < 0 ? .3 : .1) * diff;
+
+      // If the new time is similar, reuse something close to the last time
+      // left, but subtract a little to provide forward progress.
+      diff = aSeconds - aLastSeconds;
+      let diffPercent = diff / aLastSeconds * 100;
+      if (Math.abs(diff) < 5 || Math.abs(diffPercent) < 5) {
+        aSeconds = aLastSeconds - (diff < 0 ? .4 : .2);
+      }
+    }
+
+    // In the last few seconds of downloading, we are always subtracting and
+    // never adding to the time left.  Ensure that we never fall below one
+    // second left until all downloads are actually finished.
+    return aLastSeconds = Math.max(aSeconds, 1);
+  },
+
+  /**
+   * Opens a downloaded file.
+   *
+   * @param aFile
+   *        the downloaded file to be opened.
+   * @param aMimeInfo
+   *        the mime type info object.  May be null.
+   * @param aOwnerWindow
+   *        the window with which this action is associated.
+   */
+  openDownloadedFile(aFile, aMimeInfo, aOwnerWindow) {
+    if (!(aFile instanceof Ci.nsIFile)) {
+      throw new Error("aFile must be a nsIFile object");
+    }
+    if (aMimeInfo && !(aMimeInfo instanceof Ci.nsIMIMEInfo)) {
+      throw new Error("Invalid value passed for aMimeInfo");
+    }
+    if (!(aOwnerWindow instanceof Ci.nsIDOMWindow)) {
+      throw new Error("aOwnerWindow must be a dom-window object");
+    }
+
+#ifdef XP_WIN
+    let isWindowsExe = aFile.leafName.toLowerCase().endsWith(".exe");
+#else
+    let isWindowsExe = false;
+#endif
+
+    let promiseShouldLaunch;
+    // Don't prompt on Windows for .exe since there will be a native prompt.
+    if (aFile.isExecutable() && !isWindowsExe) {
+      // We get a prompter for the provided window here, even though anchoring
+      // to the most recently active window should work as well.
+      promiseShouldLaunch =
+        DownloadUIHelper.getPrompter(aOwnerWindow)
+                        .confirmLaunchExecutable(aFile.path);
+    } else {
+      promiseShouldLaunch = Promise.resolve(true);
+    }
+
+    promiseShouldLaunch.then(shouldLaunch => {
+      if (!shouldLaunch) {
+        return;
+      }
+
+      // Actually open the file.
+      try {
+        if (aMimeInfo && aMimeInfo.preferredAction == aMimeInfo.useHelperApp) {
+          aMimeInfo.launchWithFile(aFile);
+          return;
+        }
+      } catch (ex) { }
+
+      // If either we don't have the mime info, or the preferred action failed,
+      // attempt to launch the file directly.
+      try {
+        aFile.launch();
+      } catch (ex) {
+        // If launch fails, try sending it through the system's external "file:"
+        // URL handler.
+        Cc["@mozilla.org/uriloader/external-protocol-service;1"]
+          .getService(Ci.nsIExternalProtocolService)
+          .loadUrl(NetUtil.newURI(aFile));
+      }
+    }).then(null, Cu.reportError);
+  },
+
+  /**
+   * Show a downloaded file in the system file manager.
+   *
+   * @param aFile
+   *        a downloaded file.
+   */
+  showDownloadedFile(aFile) {
+    if (!(aFile instanceof Ci.nsIFile)) {
+      throw new Error("aFile must be a nsIFile object");
+    }
+    try {
+      // Show the directory containing the file and select the file.
+      aFile.reveal();
+    } catch (ex) {
+      // If reveal fails for some reason (e.g., it's not implemented on unix
+      // or the file doesn't exist), try using the parent if we have it.
+      let parent = aFile.parent;
+      if (parent) {
+        this.showDirectory(parent);
+      }
+    }
+  },
+
+  /**
+   * Show the specified folder in the system file manager.
+   *
+   * @param aDirectory
+   *        a directory to be opened with system file manager.
+   */
+  showDirectory(aDirectory) {
+    if (!(aDirectory instanceof Ci.nsIFile)) {
+      throw new Error("aDirectory must be a nsIFile object");
+    }
+    try {
+      aDirectory.launch();
+    } catch (ex) {
+      // If launch fails (probably because it's not implemented), let
+      // the OS handler try to open the directory.
+      Cc["@mozilla.org/uriloader/external-protocol-service;1"]
+        .getService(Ci.nsIExternalProtocolService)
+        .loadUrl(NetUtil.newURI(aDirectory));
+    }
+  },
+
+  /**
+   * Displays an alert message box which asks the user if they want to
+   * unblock the downloaded file or not.
+   *
+   * @param options
+   *        An object with the following properties:
+   *        {
+   *          verdict:
+   *            The detailed reason why the download was blocked, according to
+   *            the "Downloads.Error.BLOCK_VERDICT_" constants. If an unknown
+   *            reason is specified, "Downloads.Error.BLOCK_VERDICT_MALWARE" is
+   *            assumed.
+   *          window:
+   *            The window with which this action is associated.
+   *          dialogType:
+   *            String that determines which actions are available:
+   *             - "unblock" to offer just "unblock".
+   *             - "chooseUnblock" to offer "unblock" and "confirmBlock".
+   *             - "chooseOpen" to offer "open" and "confirmBlock".
+   *        }
+   *
+   * @return {Promise}
+   * @resolves String representing the action that should be executed:
+   *            - "open" to allow the download and open the file.
+   *            - "unblock" to allow the download without opening the file.
+   *            - "confirmBlock" to delete the blocked data permanently.
+   *            - "cancel" to do nothing and cancel the operation.
+   */
+  confirmUnblockDownload: Task.async(function* ({ verdict, window,
+                                                  dialogType }) {
+    let s = DownloadsCommon.strings;
+
+    // All the dialogs have an action button and a cancel button, while only
+    // some of them have an additonal button to remove the file. The cancel
+    // button must always be the one at BUTTON_POS_1 because this is the value
+    // returned by confirmEx when using ESC or closing the dialog (bug 345067).
+    let title = s.unblockHeaderUnblock;
+    let firstButtonText = s.unblockButtonUnblock;
+    let firstButtonAction = "unblock";
+    let buttonFlags =
+        (Ci.nsIPrompt.BUTTON_TITLE_IS_STRING * Ci.nsIPrompt.BUTTON_POS_0) +
+        (Ci.nsIPrompt.BUTTON_TITLE_CANCEL * Ci.nsIPrompt.BUTTON_POS_1);
+
+    switch (dialogType) {
+      case "unblock":
+        // Use only the unblock action. The default is to cancel.
+        buttonFlags += Ci.nsIPrompt.BUTTON_POS_1_DEFAULT;
+        break;
+      case "chooseUnblock":
+        // Use the unblock and remove file actions. The default is remove file.
+        buttonFlags +=
+          (Ci.nsIPrompt.BUTTON_TITLE_IS_STRING * Ci.nsIPrompt.BUTTON_POS_2) +
+          Ci.nsIPrompt.BUTTON_POS_2_DEFAULT;
+        break;
+      case "chooseOpen":
+        // Use the unblock and open file actions. The default is open file.
+        title = s.unblockHeaderOpen;
+        firstButtonText = s.unblockButtonOpen;
+        firstButtonAction = "open";
+        buttonFlags +=
+          (Ci.nsIPrompt.BUTTON_TITLE_IS_STRING * Ci.nsIPrompt.BUTTON_POS_2) +
+          Ci.nsIPrompt.BUTTON_POS_0_DEFAULT;
+        break;
+      default:
+        Cu.reportError("Unexpected dialog type: " + dialogType);
+        return "cancel";
+    }
+
+    let message;
+    switch (verdict) {
+      case Downloads.Error.BLOCK_VERDICT_UNCOMMON:
+        message = s.unblockTypeUncommon2;
+        break;
+      case Downloads.Error.BLOCK_VERDICT_POTENTIALLY_UNWANTED:
+        message = s.unblockTypePotentiallyUnwanted2;
+        break;
+      default: // Assume Downloads.Error.BLOCK_VERDICT_MALWARE
+        message = s.unblockTypeMalware;
+        break;
+    }
+    message += "\n\n" + s.unblockTip2;
+
+    Services.ww.registerNotification(function onOpen(subj, topic) {
+      if (topic == "domwindowopened" && subj instanceof Ci.nsIDOMWindow) {
+        // Make sure to listen for "DOMContentLoaded" because it is fired
+        // before the "load" event.
+        subj.addEventListener("DOMContentLoaded", function onLoad() {
+          subj.removeEventListener("DOMContentLoaded", onLoad);
+          if (subj.document.documentURI ==
+              "chrome://global/content/commonDialog.xul") {
+            Services.ww.unregisterNotification(onOpen);
+            let dialog = subj.document.getElementById("commonDialog");
+            if (dialog) {
+              // Change the dialog to use a warning icon.
+              dialog.classList.add("alert-dialog");
+            }
+          }
+        });
+      }
+    });
+
+    let rv = Services.prompt.confirmEx(window, title, message, buttonFlags,
+                                       firstButtonText, null,
+                                       s.unblockButtonConfirmBlock, null, {});
+    return [firstButtonAction, "cancel", "confirmBlock"][rv];
+  }),
+};
+
+XPCOMUtils.defineLazyGetter(this.DownloadsCommon, "log", () => {
+  return DownloadsLogger.log.bind(DownloadsLogger);
+});
+XPCOMUtils.defineLazyGetter(this.DownloadsCommon, "error", () => {
+  return DownloadsLogger.error.bind(DownloadsLogger);
+});
+
+/**
+ * Returns true if we are executing on Windows Vista or a later version.
+ */
+XPCOMUtils.defineLazyGetter(DownloadsCommon, "isWinVistaOrHigher", function () {
+  let os = Cc["@mozilla.org/xre/app-info;1"].getService(Ci.nsIXULRuntime).OS;
+  if (os != "WINNT") {
+    return false;
+  }
+  let sysInfo = Cc["@mozilla.org/system-info;1"].getService(Ci.nsIPropertyBag2);
+  return parseFloat(sysInfo.getProperty("version")) >= 6;
+});
+
+////////////////////////////////////////////////////////////////////////////////
+//// DownloadsData
+
+/**
+ * Retrieves the list of past and completed downloads from the underlying
+ * Download Manager data, and provides asynchronous notifications allowing to
+ * build a consistent view of the available data.
+ *
+ * This object responds to real-time changes in the underlying Download Manager
+ * data.  For example, the deletion of one or more downloads is notified through
+ * the nsIObserver interface, while any state or progress change is notified
+ * through the nsIDownloadProgressListener interface.
+ *
+ * Note that using this object does not automatically start the Download Manager
+ * service.  Consumers will see an empty list of downloads until the service is
+ * actually started.  This is useful to display a neutral progress indicator in
+ * the main browser window until the autostart timeout elapses.
+ *
+ * Note that DownloadsData and PrivateDownloadsData are two equivalent singleton
+ * objects, one accessing non-private downloads, and the other accessing private
+ * ones.
+ */
+function DownloadsDataCtor(aPrivate) {
+  this._isPrivate = aPrivate;
+
+  // Contains all the available Download objects and their integer state.
+  this.oldDownloadStates = new Map();
+
+  // Array of view objects that should be notified when the available download
+  // data changes.
+  this._views = [];
+}
+
+DownloadsDataCtor.prototype = {
+  /**
+   * Starts receiving events for current downloads.
+   */
+  initializeDataLink() {
+    if (!this._dataLinkInitialized) {
+      let promiseList = Downloads.getList(this._isPrivate ? Downloads.PRIVATE
+                                                          : Downloads.PUBLIC);
+      promiseList.then(list => list.addView(this)).then(null, Cu.reportError);
+      this._dataLinkInitialized = true;
+    }
+  },
+  _dataLinkInitialized: false,
+
+  /**
+   * Iterator for all the available Download objects. This is empty until the
+   * data has been loaded using the JavaScript API for downloads.
+   */
+  get downloads() {
+    return this.oldDownloadStates.keys();
+  },
+
+  /**
+   * True if there are finished downloads that can be removed from the list.
+   */
+  get canRemoveFinished() {
+    for (let download of this.downloads) {
+      // Stopped, paused, and failed downloads with partial data are removed.
+      if (download.stopped && !(download.canceled && download.hasPartialData)) {
+        return true;
+      }
+    }
+    return false;
+  },
+
+  /**
+   * Asks the back-end to remove finished downloads from the list.
+   */
+  removeFinished() {
+    let promiseList = Downloads.getList(this._isPrivate ? Downloads.PRIVATE
+                                                        : Downloads.PUBLIC);
+    promiseList.then(list => list.removeFinished())
+               .then(null, Cu.reportError);
+    let indicatorData = this._isPrivate ? PrivateDownloadsIndicatorData
+                                        : DownloadsIndicatorData;
+    indicatorData.attention = DownloadsCommon.ATTENTION_NONE;
+  },
+
+  //////////////////////////////////////////////////////////////////////////////
+  //// Integration with the asynchronous Downloads back-end
+
+  onDownloadAdded(download) {
+    // Download objects do not store the end time of downloads, as the Downloads
+    // API does not need to persist this information for all platforms. Once a
+    // download terminates on a Desktop browser, it becomes a history download,
+    // for which the end time is stored differently, as a Places annotation.
+    download.endTime = Date.now();
+
+    this.oldDownloadStates.set(download,
+                               DownloadsCommon.stateOfDownload(download));
+
+    for (let view of this._views) {
+      view.onDownloadAdded(download, true);
+    }
+  },
+
+  onDownloadChanged(download) {
+    let oldState = this.oldDownloadStates.get(download);
+    let newState = DownloadsCommon.stateOfDownload(download);
+    this.oldDownloadStates.set(download, newState);
+
+    if (oldState != newState) {
+      if (download.succeeded ||
+          (download.canceled && !download.hasPartialData) ||
+          download.error) {
+        // Store the end time that may be displayed by the views.
+        download.endTime = Date.now();
+
+        // This state transition code should actually be located in a Downloads
+        // API module (bug 941009).  Moreover, the fact that state is stored as
+        // annotations should be ideally hidden behind methods of
+        // nsIDownloadHistory (bug 830415).
+        if (!this._isPrivate) {
+          try {
+            let downloadMetaData = {
+              state: DownloadsCommon.stateOfDownload(download),
+              endTime: download.endTime,
+            };
+            if (download.succeeded) {
+              downloadMetaData.fileSize = download.target.size;
+            }
+            if (download.error && download.error.reputationCheckVerdict) {
+              downloadMetaData.reputationCheckVerdict =
+                download.error.reputationCheckVerdict;
+            }
+
+            PlacesUtils.annotations.setPageAnnotation(
+                          NetUtil.newURI(download.source.url),
+                          "downloads/metaData",
+                          JSON.stringify(downloadMetaData), 0,
+                          PlacesUtils.annotations.EXPIRE_WITH_HISTORY);
+          } catch (ex) {
+            Cu.reportError(ex);
+          }
+        }
+      }
+
+      for (let view of this._views) {
+        try {
+          view.onDownloadStateChanged(download);
+        } catch (ex) {
+          Cu.reportError(ex);
+        }
+      }
+
+      if (download.succeeded ||
+          (download.error && download.error.becauseBlocked)) {
+        this._notifyDownloadEvent("finish");
+      }
+    }
+
+    if (!download.newDownloadNotified) {
+      download.newDownloadNotified = true;
+      this._notifyDownloadEvent("start");
+    }
+
+    for (let view of this._views) {
+      view.onDownloadChanged(download);
+    }
+  },
+
+  onDownloadRemoved(download) {
+    this.oldDownloadStates.delete(download);
+
+    for (let view of this._views) {
+      view.onDownloadRemoved(download);
+    }
+  },
+
+  //////////////////////////////////////////////////////////////////////////////
+  //// Registration of views
+
+  /**
+   * Adds an object to be notified when the available download data changes.
+   * The specified object is initialized with the currently available downloads.
+   *
+   * @param aView
+   *        DownloadsView object to be added.  This reference must be passed to
+   *        removeView before termination.
+   */
+  addView(aView) {
+    this._views.push(aView);
+    this._updateView(aView);
+  },
+
+  /**
+   * Removes an object previously added using addView.
+   *
+   * @param aView
+   *        DownloadsView object to be removed.
+   */
+  removeView(aView) {
+    let index = this._views.indexOf(aView);
+    if (index != -1) {
+      this._views.splice(index, 1);
+    }
+  },
+
+  /**
+   * Ensures that the currently loaded data is added to the specified view.
+   *
+   * @param aView
+   *        DownloadsView object to be initialized.
+   */
+  _updateView(aView) {
+    // Indicate to the view that a batch loading operation is in progress.
+    aView.onDataLoadStarting();
+
+    // Sort backwards by start time, ensuring that the most recent
+    // downloads are added first regardless of their state.
+    let downloadsArray = [...this.downloads];
+    downloadsArray.sort((a, b) => b.startTime - a.startTime);
+    downloadsArray.forEach(download => aView.onDownloadAdded(download, false));
+
+    // Notify the view that all data is available.
+    aView.onDataLoadCompleted();
+  },
+
+  //////////////////////////////////////////////////////////////////////////////
+  //// Notifications sent to the most recent browser window only
+
+  /**
+   * Set to true after the first download causes the downloads panel to be
+   * displayed.
+   */
+  get panelHasShownBefore() {
+    try {
+      return Services.prefs.getBoolPref("browser.download.panel.shown");
+    } catch (ex) { }
+    return false;
+  },
+
+  set panelHasShownBefore(aValue) {
+    Services.prefs.setBoolPref("browser.download.panel.shown", aValue);
+    return aValue;
+  },
+
+  /**
+   * Displays a new or finished download notification in the most recent browser
+   * window, if one is currently available with the required privacy type.
+   *
+   * @param aType
+   *        Set to "start" for new downloads, "finish" for completed downloads.
+   */
+  _notifyDownloadEvent(aType) {
+    DownloadsCommon.log("Attempting to notify that a new download has started or finished.");
+
+    // Show the panel in the most recent browser window, if present.
+    let browserWin = RecentWindow.getMostRecentBrowserWindow({ private: this._isPrivate });
+    if (!browserWin) {
+      return;
+    }
+
+    if (this.panelHasShownBefore) {
+      // For new downloads after the first one, don't show the panel
+      // automatically, but provide a visible notification in the topmost
+      // browser window, if the status indicator is already visible.
+      DownloadsCommon.log("Showing new download notification.");
+      browserWin.DownloadsIndicatorView.showEventNotification(aType);
+      return;
+    }
+    this.panelHasShownBefore = true;
+    browserWin.DownloadsPanel.showPanel();
+  }
+};
+
+XPCOMUtils.defineLazyGetter(this, "PrivateDownloadsData", function() {
+  return new DownloadsDataCtor(true);
+});
+
+XPCOMUtils.defineLazyGetter(this, "DownloadsData", function() {
+  return new DownloadsDataCtor(false);
+});
+
+////////////////////////////////////////////////////////////////////////////////
+//// DownloadsViewPrototype
+
+/**
+ * A prototype for an object that registers itself with DownloadsData as soon
+ * as a view is registered with it.
+ */
+const DownloadsViewPrototype = {
+  //////////////////////////////////////////////////////////////////////////////
+  //// Registration of views
+
+  /**
+   * Array of view objects that should be notified when the available status
+   * data changes.
+   *
+   * SUBCLASSES MUST OVERRIDE THIS PROPERTY.
+   */
+  _views: null,
+
+  /**
+   * Determines whether this view object is over the private or non-private
+   * downloads.
+   *
+   * SUBCLASSES MUST OVERRIDE THIS PROPERTY.
+   */
+  _isPrivate: false,
+
+  /**
+   * Adds an object to be notified when the available status data changes.
+   * The specified object is initialized with the currently available status.
+   *
+   * @param aView
+   *        View object to be added.  This reference must be
+   *        passed to removeView before termination.
+   */
+  addView(aView) {
+    // Start receiving events when the first of our views is registered.
+    if (this._views.length == 0) {
+      if (this._isPrivate) {
+        PrivateDownloadsData.addView(this);
+      } else {
+        DownloadsData.addView(this);
+      }
+    }
+
+    this._views.push(aView);
+    this.refreshView(aView);
+  },
+
+  /**
+   * Updates the properties of an object previously added using addView.
+   *
+   * @param aView
+   *        View object to be updated.
+   */
+  refreshView(aView) {
+    // Update immediately even if we are still loading data asynchronously.
+    // Subclasses must provide these two functions!
+    this._refreshProperties();
+    this._updateView(aView);
+  },
+
+  /**
+   * Removes an object previously added using addView.
+   *
+   * @param aView
+   *        View object to be removed.
+   */
+  removeView(aView) {
+    let index = this._views.indexOf(aView);
+    if (index != -1) {
+      this._views.splice(index, 1);
+    }
+
+    // Stop receiving events when the last of our views is unregistered.
+    if (this._views.length == 0) {
+      if (this._isPrivate) {
+        PrivateDownloadsData.removeView(this);
+      } else {
+        DownloadsData.removeView(this);
+      }
+    }
+  },
+
+  //////////////////////////////////////////////////////////////////////////////
+  //// Callback functions from DownloadsData
+
+  /**
+   * Indicates whether we are still loading downloads data asynchronously.
+   */
+  _loading: false,
+
+  /**
+   * Called before multiple downloads are about to be loaded.
+   */
+  onDataLoadStarting() {
+    this._loading = true;
+  },
+
+  /**
+   * Called after data loading finished.
+   */
+  onDataLoadCompleted() {
+    this._loading = false;
+  },
+
+  /**
+   * Called when a new download data item is available, either during the
+   * asynchronous data load or when a new download is started.
+   *
+   * @param download
+   *        Download object that was just added.
+   * @param newest
+   *        When true, indicates that this item is the most recent and should be
+   *        added in the topmost position.  This happens when a new download is
+   *        started.  When false, indicates that the item is the least recent
+   *        with regard to the items that have been already added. The latter
+   *        generally happens during the asynchronous data load.
+   *
+   * @note Subclasses should override this.
+   */
+  onDownloadAdded(download, newest) {
+    throw Components.results.NS_ERROR_NOT_IMPLEMENTED;
+  },
+
+  /**
+   * Called when the overall state of a Download has changed. In particular,
+   * this is called only once when the download succeeds or is blocked
+   * permanently, and is never called if only the current progress changed.
+   *
+   * The onDownloadChanged notification will always be sent afterwards.
+   *
+   * @note Subclasses should override this.
+   */
+  onDownloadStateChanged(download) {
+    throw Components.results.NS_ERROR_NOT_IMPLEMENTED;
+  },
+
+  /**
+   * Called every time any state property of a Download may have changed,
+   * including progress properties.
+   *
+   * Note that progress notification changes are throttled at the Downloads.jsm
+   * API level, and there is no throttling mechanism in the front-end.
+   *
+   * @note Subclasses should override this.
+   */
+  onDownloadChanged(download) {
+    throw Components.results.NS_ERROR_NOT_IMPLEMENTED;
+  },
+
+  /**
+   * Called when a data item is removed, ensures that the widget associated with
+   * the view item is removed from the user interface.
+   *
+   * @param download
+   *        Download object that is being removed.
+   *
+   * @note Subclasses should override this.
+   */
+  onDownloadRemoved(download) {
+    throw Components.results.NS_ERROR_NOT_IMPLEMENTED;
+  },
+
+  /**
+   * Private function used to refresh the internal properties being sent to
+   * each registered view.
+   *
+   * @note Subclasses should override this.
+   */
+  _refreshProperties() {
+    throw Components.results.NS_ERROR_NOT_IMPLEMENTED;
+  },
+
+  /**
+   * Private function used to refresh an individual view.
+   *
+   * @note Subclasses should override this.
+   */
+  _updateView() {
+    throw Components.results.NS_ERROR_NOT_IMPLEMENTED;
+  },
+};
+
+////////////////////////////////////////////////////////////////////////////////
+//// DownloadsIndicatorData
+
+/**
+ * This object registers itself with DownloadsData as a view, and transforms the
+ * notifications it receives into overall status data, that is then broadcast to
+ * the registered download status indicators.
+ *
+ * Note that using this object does not automatically start the Download Manager
+ * service.  Consumers will see an empty list of downloads until the service is
+ * actually started.  This is useful to display a neutral progress indicator in
+ * the main browser window until the autostart timeout elapses.
+ */
+function DownloadsIndicatorDataCtor(aPrivate) {
+  this._isPrivate = aPrivate;
+  this._views = [];
+}
+DownloadsIndicatorDataCtor.prototype = {
+  __proto__: DownloadsViewPrototype,
+
+  /**
+   * Removes an object previously added using addView.
+   *
+   * @param aView
+   *        DownloadsIndicatorView object to be removed.
+   */
+  removeView(aView) {
+    DownloadsViewPrototype.removeView.call(this, aView);
+
+    if (this._views.length == 0) {
+      this._itemCount = 0;
+    }
+  },
+
+  //////////////////////////////////////////////////////////////////////////////
+  //// Callback functions from DownloadsData
+
+  onDataLoadCompleted() {
+    DownloadsViewPrototype.onDataLoadCompleted.call(this);
+    this._updateViews();
+  },
+
+  onDownloadAdded(download, newest) {
+    this._itemCount++;
+    this._updateViews();
+  },
+
+  onDownloadStateChanged(download) {
+    if (!download.succeeded && download.error && download.error.reputationCheckVerdict) {
+      switch (download.error.reputationCheckVerdict) {
+        case Downloads.Error.BLOCK_VERDICT_UNCOMMON: // fall-through
+        case Downloads.Error.BLOCK_VERDICT_POTENTIALLY_UNWANTED:
+          // Existing higher level attention indication trumps ATTENTION_WARNING.
+          if (this._attention != DownloadsCommon.ATTENTION_SEVERE) {
+            this.attention = DownloadsCommon.ATTENTION_WARNING;
+          }
+          break;
+        case Downloads.Error.BLOCK_VERDICT_MALWARE:
+          this.attention = DownloadsCommon.ATTENTION_SEVERE;
+          break;
+        default:
+          this.attention = DownloadsCommon.ATTENTION_SEVERE;
+          Cu.reportError("Unknown reputation verdict: " +
+                         download.error.reputationCheckVerdict);
+      }
+    } else if (download.succeeded) {
+      // Existing higher level attention indication trumps ATTENTION_SUCCESS.
+      if (this._attention != DownloadsCommon.ATTENTION_SEVERE &&
+          this._attention != DownloadsCommon.ATTENTION_WARNING) {
+        this.attention = DownloadsCommon.ATTENTION_SUCCESS;
+      }
+    } else if (download.error) {
+      // Existing higher level attention indication trumps ATTENTION_WARNING.
+      if (this._attention != DownloadsCommon.ATTENTION_SEVERE) {
+        this.attention = DownloadsCommon.ATTENTION_WARNING;
+      }
+    }
+
+    // Since the state of a download changed, reset the estimated time left.
+    this._lastRawTimeLeft = -1;
+    this._lastTimeLeft = -1;
+  },
+
+  onDownloadChanged(download) {
+    this._updateViews();
+  },
+
+  onDownloadRemoved(download) {
+    this._itemCount--;
+    this._updateViews();
+  },
+
+  //////////////////////////////////////////////////////////////////////////////
+  //// Propagation of properties to our views
+
+  // The following properties are updated by _refreshProperties and are then
+  // propagated to the views.  See _refreshProperties for details.
+  _hasDownloads: false,
+  _counter: "",
+  _percentComplete: -1,
+  _paused: false,
+
+  /**
+   * Indicates whether the download indicators should be highlighted.
+   */
+  set attention(aValue) {
+    this._attention = aValue;
+    this._updateViews();
+    return aValue;
+  },
+  _attention: DownloadsCommon.ATTENTION_NONE,
+
+  /**
+   * Indicates whether the user is interacting with downloads, thus the
+   * attention indication should not be shown even if requested.
+   */
+  set attentionSuppressed(aValue) {
+    this._attentionSuppressed = aValue;
+    this._attention = DownloadsCommon.ATTENTION_NONE;
+    this._updateViews();
+    return aValue;
+  },
+  _attentionSuppressed: false,
+
+  /**
+   * Computes aggregate values and propagates the changes to our views.
+   */
+  _updateViews() {
+    // Do not update the status indicators during batch loads of download items.
+    if (this._loading) {
+      return;
+    }
+
+    this._refreshProperties();
+    this._views.forEach(this._updateView, this);
+  },
+
+  /**
+   * Updates the specified view with the current aggregate values.
+   *
+   * @param aView
+   *        DownloadsIndicatorView object to be updated.
+   */
+  _updateView(aView) {
+    aView.hasDownloads = this._hasDownloads;
+    aView.counter = this._counter;
+    aView.percentComplete = this._percentComplete;
+    aView.paused = this._paused;
+    aView.attention = this._attentionSuppressed ? DownloadsCommon.ATTENTION_NONE
+                                                : this._attention;
+  },
+
+  //////////////////////////////////////////////////////////////////////////////
+  //// Property updating based on current download status
+
+  /**
+   * Number of download items that are available to be displayed.
+   */
+  _itemCount: 0,
+
+  /**
+   * Floating point value indicating the last number of seconds estimated until
+   * the longest download will finish.  We need to store this value so that we
+   * don't continuously apply smoothing if the actual download state has not
+   * changed.  This is set to -1 if the previous value is unknown.
+   */
+  _lastRawTimeLeft: -1,
+
+  /**
+   * Last number of seconds estimated until all in-progress downloads with a
+   * known size and speed will finish.  This value is stored to allow smoothing
+   * in case of small variations.  This is set to -1 if the previous value is
+   * unknown.
+   */
+  _lastTimeLeft: -1,
+
+  /**
+   * A generator function for the Download objects this summary is currently
+   * interested in. This generator is passed off to summarizeDownloads in order
+   * to generate statistics about the downloads we care about - in this case,
+   * it's all active downloads.
+   */
+  * _activeDownloads() {
+    let downloads = this._isPrivate ? PrivateDownloadsData.downloads
+                                    : DownloadsData.downloads;
+    for (let download of downloads) {
+      if (!download.stopped || (download.canceled && download.hasPartialData)) {
+        yield download;
+      }
+    }
+  },
+
+  /**
+   * Computes aggregate values based on the current state of downloads.
+   */
+  _refreshProperties() {
+    let summary =
+      DownloadsCommon.summarizeDownloads(this._activeDownloads());
+
+    // Determine if the indicator should be shown or get attention.
+    this._hasDownloads = (this._itemCount > 0);
+
+    // If all downloads are paused, show the progress indicator as paused.
+    this._paused = summary.numActive > 0 &&
+                   summary.numActive == summary.numPaused;
+
+    this._percentComplete = summary.percentComplete;
+
+    // Display the estimated time left, if present.
+    if (summary.rawTimeLeft == -1) {
+      // There are no downloads with a known time left.
+      this._lastRawTimeLeft = -1;
+      this._lastTimeLeft = -1;
+      this._counter = "";
+    } else {
+      // Compute the new time left only if state actually changed.
+      if (this._lastRawTimeLeft != summary.rawTimeLeft) {
+        this._lastRawTimeLeft = summary.rawTimeLeft;
+        this._lastTimeLeft = DownloadsCommon.smoothSeconds(summary.rawTimeLeft,
+                                                           this._lastTimeLeft);
+      }
+      this._counter = DownloadsCommon.formatTimeLeft(this._lastTimeLeft);
+    }
+  }
+};
+
+XPCOMUtils.defineLazyGetter(this, "PrivateDownloadsIndicatorData", function() {
+  return new DownloadsIndicatorDataCtor(true);
+});
+
+XPCOMUtils.defineLazyGetter(this, "DownloadsIndicatorData", function() {
+  return new DownloadsIndicatorDataCtor(false);
+});
+
+////////////////////////////////////////////////////////////////////////////////
+//// DownloadsSummaryData
+
+/**
+ * DownloadsSummaryData is a view for DownloadsData that produces a summary
+ * of all downloads after a certain exclusion point aNumToExclude. For example,
+ * if there were 5 downloads in progress, and a DownloadsSummaryData was
+ * constructed with aNumToExclude equal to 3, then that DownloadsSummaryData
+ * would produce a summary of the last 2 downloads.
+ *
+ * @param aIsPrivate
+ *        True if the browser window which owns the download button is a private
+ *        window.
+ * @param aNumToExclude
+ *        The number of items to exclude from the summary, starting from the
+ *        top of the list.
+ */
+function DownloadsSummaryData(aIsPrivate, aNumToExclude) {
+  this._numToExclude = aNumToExclude;
+  // Since we can have multiple instances of DownloadsSummaryData, we
+  // override these values from the prototype so that each instance can be
+  // completely separated from one another.
+  this._loading = false;
+
+  this._downloads = [];
+
+  // Floating point value indicating the last number of seconds estimated until
+  // the longest download will finish.  We need to store this value so that we
+  // don't continuously apply smoothing if the actual download state has not
+  // changed.  This is set to -1 if the previous value is unknown.
+  this._lastRawTimeLeft = -1;
+
+  // Last number of seconds estimated until all in-progress downloads with a
+  // known size and speed will finish.  This value is stored to allow smoothing
+  // in case of small variations.  This is set to -1 if the previous value is
+  // unknown.
+  this._lastTimeLeft = -1;
+
+  // The following properties are updated by _refreshProperties and are then
+  // propagated to the views.
+  this._showingProgress = false;
+  this._details = "";
+  this._description = "";
+  this._numActive = 0;
+  this._percentComplete = -1;
+
+  this._isPrivate = aIsPrivate;
+  this._views = [];
+}
+
+DownloadsSummaryData.prototype = {
+  __proto__: DownloadsViewPrototype,
+
+  /**
+   * Removes an object previously added using addView.
+   *
+   * @param aView
+   *        DownloadsSummary view to be removed.
+   */
+  removeView(aView) {
+    DownloadsViewPrototype.removeView.call(this, aView);
+
+    if (this._views.length == 0) {
+      // Clear out our collection of Download objects. If we ever have
+      // another view registered with us, this will get re-populated.
+      this._downloads = [];
+    }
+  },
+
+  //////////////////////////////////////////////////////////////////////////////
+  //// Callback functions from DownloadsData - see the documentation in
+  //// DownloadsViewPrototype for more information on what these functions
+  //// are used for.
+
+  onDataLoadCompleted() {
+    DownloadsViewPrototype.onDataLoadCompleted.call(this);
+    this._updateViews();
+  },
+
+  onDownloadAdded(download, newest) {
+    if (newest) {
+      this._downloads.unshift(download);
+    } else {
+      this._downloads.push(download);
+    }
+
+    this._updateViews();
+  },
+
+  onDownloadStateChanged() {
+    // Since the state of a download changed, reset the estimated time left.
+    this._lastRawTimeLeft = -1;
+    this._lastTimeLeft = -1;
+  },
+
+  onDownloadChanged() {
+    this._updateViews();
+  },
+
+  onDownloadRemoved(download) {
+    let itemIndex = this._downloads.indexOf(download);
+    this._downloads.splice(itemIndex, 1);
+    this._updateViews();
+  },
+
+  //////////////////////////////////////////////////////////////////////////////
+  //// Propagation of properties to our views
+
+  /**
+   * Computes aggregate values and propagates the changes to our views.
+   */
+  _updateViews() {
+    // Do not update the status indicators during batch loads of download items.
+    if (this._loading) {
+      return;
+    }
+
+    this._refreshProperties();
+    this._views.forEach(this._updateView, this);
+  },
+
+  /**
+   * Updates the specified view with the current aggregate values.
+   *
+   * @param aView
+   *        DownloadsIndicatorView object to be updated.
+   */
+  _updateView(aView) {
+    aView.showingProgress = this._showingProgress;
+    aView.percentComplete = this._percentComplete;
+    aView.description = this._description;
+    aView.details = this._details;
+  },
+
+  //////////////////////////////////////////////////////////////////////////////
+  //// Property updating based on current download status
+
+  /**
+   * A generator function for the Download objects this summary is currently
+   * interested in. This generator is passed off to summarizeDownloads in order
+   * to generate statistics about the downloads we care about - in this case,
+   * it's the downloads in this._downloads after the first few to exclude,
+   * which was set when constructing this DownloadsSummaryData instance.
+   */
+  * _downloadsForSummary() {
+    if (this._downloads.length > 0) {
+      for (let i = this._numToExclude; i < this._downloads.length; ++i) {
+        yield this._downloads[i];
+      }
+    }
+  },
+
+  /**
+   * Computes aggregate values based on the current state of downloads.
+   */
+  _refreshProperties() {
+    // Pre-load summary with default values.
+    let summary =
+      DownloadsCommon.summarizeDownloads(this._downloadsForSummary());
+
+    this._description = DownloadsCommon.strings
+                                       .otherDownloads3(summary.numDownloading);
+    this._percentComplete = summary.percentComplete;
+
+    // Only show the downloading items.
+    this._showingProgress = summary.numDownloading > 0;
+
+    // Display the estimated time left, if present.
+    if (summary.rawTimeLeft == -1) {
+      // There are no downloads with a known time left.
+      this._lastRawTimeLeft = -1;
+      this._lastTimeLeft = -1;
+      this._details = "";
+    } else {
+      // Compute the new time left only if state actually changed.
+      if (this._lastRawTimeLeft != summary.rawTimeLeft) {
+        this._lastRawTimeLeft = summary.rawTimeLeft;
+        this._lastTimeLeft = DownloadsCommon.smoothSeconds(summary.rawTimeLeft,
+                                                           this._lastTimeLeft);
+      }
+      [this._details] = DownloadUtils.getDownloadStatusNoRate(
+        summary.totalTransferred, summary.totalSize, summary.slowestSpeed,
+        this._lastTimeLeft);
+    }
+  },
+}