Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1716 insertions, 0 deletions

diff --git a/browser/components/downloads/content/downloads.js b/browser/components/downloads/content/downloads.js
new file mode 100644
index 0000000000..10eb8a2feb
--- /dev/null
+++ b/browser/components/downloads/content/downloads.js
@@ -0,0 +1,1716 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* 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/. */
+/* eslint-env mozilla/browser-window */
+
+/**
+ * Handles the Downloads panel user interface for each browser window.
+ *
+ * This file includes the following constructors and global objects:
+ *
+ * DownloadsPanel
+ * Main entry point for the downloads panel interface.
+ *
+ * DownloadsView
+ * Builds and updates the downloads list widget, responding to changes in the
+ * download state and real-time data.  In addition, handles part of the user
+ * interaction events raised by the downloads list widget.
+ *
+ * DownloadsViewItem
+ * Builds and updates a single item in the downloads list widget, responding to
+ * changes in the download state and real-time data, and handles the user
+ * interaction events related to a single item in the downloads list widgets.
+ *
+ * DownloadsViewController
+ * Handles part of the user interaction events raised by the downloads list
+ * widget, in particular the "commands" that apply to multiple items, and
+ * dispatches the commands that apply to individual items.
+ */
+
+"use strict";
+
+var { XPCOMUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/XPCOMUtils.sys.mjs"
+);
+
+ChromeUtils.defineESModuleGetters(this, {
+  DownloadsViewUI: "resource:///modules/DownloadsViewUI.sys.mjs",
+  FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
+  PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
+});
+ChromeUtils.defineModuleGetter(
+  this,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
+
+const { Integration } = ChromeUtils.importESModule(
+  "resource://gre/modules/Integration.sys.mjs"
+);
+
+/* global DownloadIntegration */
+Integration.downloads.defineESModuleGetter(
+  this,
+  "DownloadIntegration",
+  "resource://gre/modules/DownloadIntegration.sys.mjs"
+);
+
+// DownloadsPanel
+
+/**
+ * Main entry point for the downloads panel interface.
+ */
+var DownloadsPanel = {
+  // Initialization and termination
+
+  /**
+   * Timeout that re-enables previously disabled download items in the downloads panel
+   * after some time has passed.
+   */
+  _delayTimeout: null,
+
+  /**
+   * Internal state of the downloads panel, based on one of the kState
+   * constants.  This is not the same state as the XUL panel element.
+   */
+  _state: 0,
+
+  /** The panel is not linked to downloads data yet. */
+  get kStateUninitialized() {
+    return 0;
+  },
+  /** This object is linked to data, but the panel is invisible. */
+  get kStateHidden() {
+    return 1;
+  },
+  /** The panel will be shown as soon as possible. */
+  get kStateWaitingData() {
+    return 2;
+  },
+  /** The panel is open. */
+  get kStateShown() {
+    return 3;
+  },
+
+  /**
+   * Starts loading the download data in background, without opening the panel.
+   * Use showPanel instead to load the data and open the panel at the same time.
+   */
+  initialize() {
+    DownloadsCommon.log(
+      "Attempting to initialize DownloadsPanel for a window."
+    );
+
+    if (DownloadIntegration.downloadSpamProtection) {
+      DownloadIntegration.downloadSpamProtection.register(
+        DownloadsView,
+        window
+      );
+    }
+
+    if (this._state != this.kStateUninitialized) {
+      DownloadsCommon.log("DownloadsPanel is already initialized.");
+      return;
+    }
+    this._state = this.kStateHidden;
+
+    window.addEventListener("unload", this.onWindowUnload);
+
+    // Load and resume active downloads if required.  If there are downloads to
+    // be shown in the panel, they will be loaded asynchronously.
+    DownloadsCommon.initializeAllDataLinks();
+
+    // Now that data loading has eventually started, load the required XUL
+    // elements and initialize our views.
+
+    this.panel.hidden = false;
+    DownloadsViewController.initialize();
+    DownloadsCommon.log("Attaching DownloadsView...");
+    DownloadsCommon.getData(window).addView(DownloadsView);
+    DownloadsCommon.getSummary(window, DownloadsView.kItemCountLimit).addView(
+      DownloadsSummary
+    );
+
+    DownloadsCommon.log(
+      "DownloadsView attached - the panel for this window",
+      "should now see download items come in."
+    );
+    DownloadsPanel._attachEventListeners();
+    DownloadsCommon.log("DownloadsPanel initialized.");
+  },
+
+  /**
+   * Closes the downloads panel and frees the internal resources related to the
+   * downloads.  The downloads panel can be reopened later, even after this
+   * function has been called.
+   */
+  terminate() {
+    DownloadsCommon.log("Attempting to terminate DownloadsPanel for a window.");
+    if (this._state == this.kStateUninitialized) {
+      DownloadsCommon.log(
+        "DownloadsPanel was never initialized. Nothing to do."
+      );
+      return;
+    }
+
+    window.removeEventListener("unload", this.onWindowUnload);
+
+    // Ensure that the panel is closed before shutting down.
+    this.hidePanel();
+
+    DownloadsViewController.terminate();
+    DownloadsCommon.getData(window).removeView(DownloadsView);
+    DownloadsCommon.getSummary(
+      window,
+      DownloadsView.kItemCountLimit
+    ).removeView(DownloadsSummary);
+    this._unattachEventListeners();
+
+    if (DownloadIntegration.downloadSpamProtection) {
+      DownloadIntegration.downloadSpamProtection.unregister(window);
+    }
+
+    this._state = this.kStateUninitialized;
+
+    DownloadsSummary.active = false;
+    DownloadsCommon.log("DownloadsPanel terminated.");
+  },
+
+  // Panel interface
+
+  /**
+   * Main panel element in the browser window.
+   */
+  get panel() {
+    delete this.panel;
+    return (this.panel = document.getElementById("downloadsPanel"));
+  },
+
+  /**
+   * Starts opening the downloads panel interface, anchored to the downloads
+   * button of the browser window.  The list of downloads to display is
+   * initialized the first time this method is called, and the panel is shown
+   * only when data is ready.
+   */
+  showPanel(openedManually = false, isKeyPress = false) {
+    Services.telemetry.scalarAdd("downloads.panel_shown", 1);
+    DownloadsCommon.log("Opening the downloads panel.");
+
+    this._openedManually = openedManually;
+    this._preventFocusRing = !openedManually || !isKeyPress;
+
+    if (this.isPanelShowing) {
+      DownloadsCommon.log("Panel is already showing - focusing instead.");
+      this._focusPanel();
+      return;
+    }
+
+    // As a belt-and-suspenders check, ensure the button is not hidden.
+    DownloadsButton.unhide();
+
+    this.initialize();
+    // Delay displaying the panel because this function will sometimes be
+    // called while another window is closing (like the window for selecting
+    // whether to save or open the file), and that would cause the panel to
+    // close immediately.
+    setTimeout(() => this._openPopupIfDataReady(), 0);
+
+    DownloadsCommon.log("Waiting for the downloads panel to appear.");
+    this._state = this.kStateWaitingData;
+  },
+
+  /**
+   * Hides the downloads panel, if visible, but keeps the internal state so that
+   * the panel can be reopened quickly if required.
+   */
+  hidePanel() {
+    DownloadsCommon.log("Closing the downloads panel.");
+
+    if (!this.isPanelShowing) {
+      DownloadsCommon.log("Downloads panel is not showing - nothing to do.");
+      return;
+    }
+
+    PanelMultiView.hidePopup(this.panel);
+
+    // Ensure that we allow the panel to be reopened.  Note that, if the popup
+    // was open, then the onPopupHidden event handler has already updated the
+    // current state, otherwise we must update the state ourselves.
+    this._state = this.kStateHidden;
+    DownloadsCommon.log("Downloads panel is now closed.");
+  },
+
+  /**
+   * Indicates whether the panel is shown or will be shown.
+   */
+  get isPanelShowing() {
+    return (
+      this._state == this.kStateWaitingData || this._state == this.kStateShown
+    );
+  },
+
+  handleEvent(aEvent) {
+    switch (aEvent.type) {
+      case "mousemove":
+        if (
+          !DownloadsView.contextMenuOpen &&
+          !DownloadsView.subViewOpen &&
+          this.panel.contains(document.activeElement)
+        ) {
+          // Let mouse movement remove focus rings and reset focus in the panel.
+          // This behavior is copied from PanelMultiView.
+          document.activeElement.blur();
+          DownloadsView.richListBox.removeAttribute("force-focus-visible");
+          this._preventFocusRing = true;
+          this._focusPanel();
+        }
+        break;
+      case "keydown":
+        this._onKeyDown(aEvent);
+        break;
+      case "keypress":
+        this._onKeyPress(aEvent);
+        break;
+      case "focus":
+      case "select":
+        this._onSelect(aEvent);
+        break;
+    }
+  },
+
+  // Callback functions from DownloadsView
+
+  /**
+   * Called after data loading finished.
+   */
+  onViewLoadCompleted() {
+    this._openPopupIfDataReady();
+  },
+
+  // User interface event functions
+
+  onWindowUnload() {
+    // This function is registered as an event listener, we can't use "this".
+    DownloadsPanel.terminate();
+  },
+
+  onPopupShown(aEvent) {
+    // Ignore events raised by nested popups.
+    if (aEvent.target != aEvent.currentTarget) {
+      return;
+    }
+
+    DownloadsCommon.log("Downloads panel has shown.");
+    this._state = this.kStateShown;
+
+    // Since at most one popup is open at any given time, we can set globally.
+    DownloadsCommon.getIndicatorData(window).attentionSuppressed |=
+      DownloadsCommon.SUPPRESS_PANEL_OPEN;
+
+    // Ensure that the first item is selected when the panel is focused.
+    if (DownloadsView.richListBox.itemCount > 0) {
+      DownloadsView.richListBox.selectedIndex = 0;
+    }
+
+    this._focusPanel();
+  },
+
+  onPopupHidden(aEvent) {
+    // Ignore events raised by nested popups.
+    if (aEvent.target != aEvent.currentTarget) {
+      return;
+    }
+
+    DownloadsCommon.log("Downloads panel has hidden.");
+
+    if (this._delayTimeout) {
+      DownloadsView.richListBox.removeAttribute("disabled");
+      clearTimeout(this._delayTimeout);
+      this._stopWatchingForSpammyDownloadActivation();
+      this._delayTimeout = null;
+    }
+
+    DownloadsView.richListBox.removeAttribute("force-focus-visible");
+
+    // Since at most one popup is open at any given time, we can set globally.
+    DownloadsCommon.getIndicatorData(
+      window
+    ).attentionSuppressed &= ~DownloadsCommon.SUPPRESS_PANEL_OPEN;
+
+    // Allow the anchor to be hidden.
+    DownloadsButton.releaseAnchor();
+
+    // Allow the panel to be reopened.
+    this._state = this.kStateHidden;
+  },
+
+  // Related operations
+
+  /**
+   * Shows or focuses the user interface dedicated to downloads history.
+   */
+  showDownloadsHistory() {
+    DownloadsCommon.log("Showing download history.");
+    // Hide the panel before showing another window, otherwise focus will return
+    // to the browser window when the panel closes automatically.
+    this.hidePanel();
+
+    BrowserDownloadsUI();
+  },
+
+  // Internal functions
+
+  /**
+   * Attach event listeners to a panel element. These listeners should be
+   * removed in _unattachEventListeners. This is called automatically after the
+   * panel has successfully loaded.
+   */
+  _attachEventListeners() {
+    // Handle keydown to support accel-V.
+    this.panel.addEventListener("keydown", this);
+    // Handle keypress to be able to preventDefault() events before they reach
+    // the richlistbox, for keyboard navigation.
+    this.panel.addEventListener("keypress", this);
+    this.panel.addEventListener("mousemove", this);
+    DownloadsView.richListBox.addEventListener("focus", this);
+    DownloadsView.richListBox.addEventListener("select", this);
+  },
+
+  /**
+   * Unattach event listeners that were added in _attachEventListeners. This
+   * is called automatically on panel termination.
+   */
+  _unattachEventListeners() {
+    this.panel.removeEventListener("keydown", this);
+    this.panel.removeEventListener("keypress", this);
+    this.panel.removeEventListener("mousemove", this);
+    DownloadsView.richListBox.removeEventListener("focus", this);
+    DownloadsView.richListBox.removeEventListener("select", this);
+  },
+
+  _onKeyPress(aEvent) {
+    // Handle unmodified keys only.
+    if (aEvent.altKey || aEvent.ctrlKey || aEvent.shiftKey || aEvent.metaKey) {
+      return;
+    }
+
+    // Pass keypress events to the richlistbox view when it's focused.
+    if (document.activeElement === DownloadsView.richListBox) {
+      DownloadsView.onDownloadKeyPress(aEvent);
+    }
+  },
+
+  /**
+   * Keydown listener that listens for the keys to start key focusing, as well
+   * as the the accel-V "paste" event, which initiates a file download if the
+   * pasted item can be resolved to a URI.
+   */
+  _onKeyDown(aEvent) {
+    if (DownloadsView.richListBox.hasAttribute("disabled")) {
+      this._handlePotentiallySpammyDownloadActivation(aEvent);
+      return;
+    }
+
+    let richListBox = DownloadsView.richListBox;
+
+    // If the user has pressed the up or down cursor key, force-enable focus
+    // indicators for the richlistbox.  :focus-visible doesn't work in this case
+    // because the the focused element may not change here if the richlistbox
+    // already had focus.  The force-focus-visible attribute will be removed
+    // again if the user moves the mouse on the panel or if the panel is closed.
+    if (
+      aEvent.keyCode == aEvent.DOM_VK_UP ||
+      aEvent.keyCode == aEvent.DOM_VK_DOWN
+    ) {
+      richListBox.setAttribute("force-focus-visible", "true");
+    }
+
+    // If the footer is focused and the downloads list has at least 1 element
+    // in it, focus the last element in the list when going up.
+    if (aEvent.keyCode == aEvent.DOM_VK_UP && richListBox.firstElementChild) {
+      if (
+        document
+          .getElementById("downloadsFooter")
+          .contains(document.activeElement)
+      ) {
+        richListBox.selectedItem = richListBox.lastElementChild;
+        richListBox.focus();
+        aEvent.preventDefault();
+        return;
+      }
+    }
+
+    if (aEvent.keyCode == aEvent.DOM_VK_DOWN) {
+      // If the last element in the list is selected, or the footer is already
+      // focused, focus the footer.
+      if (
+        richListBox.selectedItem === richListBox.lastElementChild ||
+        document
+          .getElementById("downloadsFooter")
+          .contains(document.activeElement)
+      ) {
+        richListBox.selectedIndex = -1;
+        DownloadsFooter.focus();
+        aEvent.preventDefault();
+        return;
+      }
+    }
+
+    let pasting =
+      aEvent.keyCode == aEvent.DOM_VK_V && aEvent.getModifierState("Accel");
+
+    if (!pasting) {
+      return;
+    }
+
+    DownloadsCommon.log("Received a paste event.");
+
+    let trans = Cc["@mozilla.org/widget/transferable;1"].createInstance(
+      Ci.nsITransferable
+    );
+    trans.init(null);
+    let flavors = ["text/x-moz-url", "text/unicode"];
+    flavors.forEach(trans.addDataFlavor);
+    Services.clipboard.getData(trans, Services.clipboard.kGlobalClipboard);
+    // Getting the data or creating the nsIURI might fail
+    try {
+      let data = {};
+      trans.getAnyTransferData({}, data);
+      let [url, name] = data.value
+        .QueryInterface(Ci.nsISupportsString)
+        .data.split("\n");
+      if (!url) {
+        return;
+      }
+
+      let uri = NetUtil.newURI(url);
+      DownloadsCommon.log("Pasted URL seems valid. Starting download.");
+      DownloadURL(uri.spec, name, document);
+    } catch (ex) {}
+  },
+
+  _onSelect() {
+    let richlistbox = DownloadsView.richListBox;
+    richlistbox.itemChildren.forEach(item => {
+      let button = item.querySelector("button");
+      if (item.selected) {
+        button.removeAttribute("tabindex");
+      } else {
+        button.setAttribute("tabindex", -1);
+      }
+    });
+  },
+
+  /**
+   * Move focus to the main element in the downloads panel, unless another
+   * element in the panel is already focused.
+   */
+  _focusPanel() {
+    // We may be invoked while the panel is still waiting to be shown.
+    if (this._state != this.kStateShown) {
+      return;
+    }
+
+    if (document.activeElement && this.panel.contains(document.activeElement)) {
+      return;
+    }
+    let focusOptions = {};
+    if (this._preventFocusRing) {
+      focusOptions.focusVisible = false;
+    }
+    if (DownloadsView.richListBox.itemCount > 0) {
+      DownloadsView.richListBox.selectedIndex = 0;
+      DownloadsView.richListBox.focus(focusOptions);
+    } else {
+      DownloadsFooter.focus(focusOptions);
+    }
+  },
+
+  _delayPopupItems() {
+    DownloadsView.richListBox.setAttribute("disabled", true);
+    this._startWatchingForSpammyDownloadActivation();
+
+    this._refreshDelayTimer();
+  },
+
+  _refreshDelayTimer() {
+    // If timeout already exists, overwrite it to avoid multiple timeouts.
+    if (this._delayTimeout) {
+      clearTimeout(this._delayTimeout);
+    }
+
+    let delay = Services.prefs.getIntPref("security.dialog_enable_delay");
+    this._delayTimeout = setTimeout(() => {
+      DownloadsView.richListBox.removeAttribute("disabled");
+      this._stopWatchingForSpammyDownloadActivation();
+      this._focusPanel();
+      this._delayTimeout = null;
+    }, delay);
+  },
+
+  _startWatchingForSpammyDownloadActivation() {
+    Services.els.addSystemEventListener(window, "keydown", this, true);
+  },
+
+  _lastBeepTime: 0,
+  _handlePotentiallySpammyDownloadActivation(aEvent) {
+    if (aEvent.key == "Enter" || aEvent.key == " ") {
+      // Throttle our beeping to a maximum of once per second, otherwise it
+      // appears on Win10 that beeps never make it through at all.
+      if (Date.now() - this._lastBeepTime > 1000) {
+        Cc["@mozilla.org/sound;1"].getService(Ci.nsISound).beep();
+        this._lastBeepTime = Date.now();
+      }
+
+      this._refreshDelayTimer();
+    }
+  },
+
+  _stopWatchingForSpammyDownloadActivation() {
+    Services.els.removeSystemEventListener(window, "keydown", this, true);
+  },
+
+  /**
+   * Opens the downloads panel when data is ready to be displayed.
+   */
+  _openPopupIfDataReady() {
+    // We don't want to open the popup if we already displayed it, or if we are
+    // still loading data.
+    if (this._state != this.kStateWaitingData || DownloadsView.loading) {
+      return;
+    }
+
+    // At this point, if the window is minimized, opening the panel could fail
+    // without any notification, and there would be no way to either open or
+    // close the panel any more.  To prevent this, check if the window is
+    // minimized and in that case force the panel to the closed state.
+    if (window.windowState == window.STATE_MINIMIZED) {
+      this._state = this.kStateHidden;
+      return;
+    }
+
+    // Ensure the anchor is visible.  If that is not possible, show the panel
+    // anchored to the top area of the window, near the default anchor position.
+    let anchor = DownloadsButton.getAnchor();
+
+    if (!anchor) {
+      DownloadsCommon.error("Downloads button cannot be found.");
+      this._state = this.kStateHidden;
+      return;
+    }
+
+    let onBookmarksToolbar = !!anchor.closest("#PersonalToolbar");
+    this.panel.classList.toggle("bookmarks-toolbar", onBookmarksToolbar);
+
+    // When the panel is opened, we check if the target files of visible items
+    // still exist, and update the allowed items interactions accordingly.  We
+    // do these checks on a background thread, and don't prevent the panel to
+    // be displayed while these checks are being performed.
+    for (let viewItem of DownloadsView._visibleViewItems.values()) {
+      viewItem.download.refresh().catch(Cu.reportError);
+    }
+
+    DownloadsCommon.log("Opening downloads panel popup.");
+
+    // Delay displaying the panel because this function will sometimes be
+    // called while another window is closing (like the window for selecting
+    // whether to save or open the file), and that would cause the panel to
+    // close immediately.
+    setTimeout(() => {
+      PanelMultiView.openPopup(
+        this.panel,
+        anchor,
+        "bottomright topright",
+        0,
+        0,
+        false,
+        null
+      ).catch(e => {
+        console.error(e);
+        this._state = this.kStateHidden;
+      });
+
+      if (!this._openedManually) {
+        this._delayPopupItems();
+      }
+    }, 0);
+  },
+};
+
+XPCOMUtils.defineConstant(this, "DownloadsPanel", DownloadsPanel);
+
+// DownloadsView
+
+/**
+ * Builds and updates the downloads list widget, responding to changes in the
+ * download state and real-time data.  In addition, handles part of the user
+ * interaction events raised by the downloads list widget.
+ */
+var DownloadsView = {
+  // Functions handling download items in the list
+
+  /**
+   * Maximum number of items shown by the list at any given time.
+   */
+  kItemCountLimit: 5,
+
+  /**
+   * Indicates whether there is a DownloadsBlockedSubview open.
+   */
+  subViewOpen: false,
+
+  /**
+   * Indicates whether we are still loading downloads data asynchronously.
+   */
+  loading: false,
+
+  /**
+   * Ordered array of all Download objects.  We need to keep this array because
+   * only a limited number of items are shown at once, and if an item that is
+   * currently visible is removed from the list, we might need to take another
+   * item from the array and make it appear at the bottom.
+   */
+  _downloads: [],
+
+  /**
+   * Associates the visible Download objects with their corresponding
+   * DownloadsViewItem object.  There is a limited number of view items in the
+   * panel at any given time.
+   */
+  _visibleViewItems: new Map(),
+
+  /**
+   * Called when the number of items in the list changes.
+   */
+  _itemCountChanged() {
+    DownloadsCommon.log(
+      "The downloads item count has changed - we are tracking",
+      this._downloads.length,
+      "downloads in total."
+    );
+    let count = this._downloads.length;
+    let hiddenCount = count - this.kItemCountLimit;
+
+    if (count > 0) {
+      DownloadsCommon.log(
+        "Setting the panel's hasdownloads attribute to true."
+      );
+      DownloadsPanel.panel.setAttribute("hasdownloads", "true");
+    } else {
+      DownloadsCommon.log("Removing the panel's hasdownloads attribute.");
+      DownloadsPanel.panel.removeAttribute("hasdownloads");
+    }
+
+    // If we've got some hidden downloads, we should activate the
+    // DownloadsSummary. The DownloadsSummary will determine whether or not
+    // it's appropriate to actually display the summary.
+    DownloadsSummary.active = hiddenCount > 0;
+  },
+
+  /**
+   * Element corresponding to the list of downloads.
+   */
+  get richListBox() {
+    delete this.richListBox;
+    return (this.richListBox = document.getElementById("downloadsListBox"));
+  },
+
+  /**
+   * Element corresponding to the button for showing more downloads.
+   */
+  get downloadsHistory() {
+    delete this.downloadsHistory;
+    return (this.downloadsHistory = document.getElementById(
+      "downloadsHistory"
+    ));
+  },
+
+  // Callback functions from DownloadsData
+
+  /**
+   * Called before multiple downloads are about to be loaded.
+   */
+  onDownloadBatchStarting() {
+    DownloadsCommon.log("onDownloadBatchStarting called for DownloadsView.");
+    this.loading = true;
+  },
+
+  /**
+   * Called after data loading finished.
+   */
+  onDownloadBatchEnded() {
+    DownloadsCommon.log("onDownloadBatchEnded called for DownloadsView.");
+
+    this.loading = false;
+
+    // We suppressed item count change notifications during the batch load, at
+    // this point we should just call the function once.
+    this._itemCountChanged();
+
+    // Notify the panel that all the initially available downloads have been
+    // loaded.  This ensures that the interface is visible, if still required.
+    DownloadsPanel.onViewLoadCompleted();
+  },
+
+  /**
+   * Called when a new download data item is available, either during the
+   * asynchronous data load or when a new download is started.
+   *
+   * @param aDownload
+   *        Download object that was just added.
+   */
+  onDownloadAdded(download) {
+    DownloadsCommon.log("A new download data item was added");
+
+    this._downloads.unshift(download);
+
+    // The newly added item is visible in the panel and we must add the
+    // corresponding element. If the list overflows, remove the last item from
+    // the panel to make room for the new one that we just added at the top.
+    this._addViewItem(download, true);
+    if (this._downloads.length > this.kItemCountLimit) {
+      this._removeViewItem(this._downloads[this.kItemCountLimit]);
+    }
+
+    // For better performance during batch loads, don't update the count for
+    // every item, because the interface won't be visible until load finishes.
+    if (!this.loading) {
+      this._itemCountChanged();
+    }
+  },
+
+  onDownloadChanged(download) {
+    let viewItem = this._visibleViewItems.get(download);
+    if (viewItem) {
+      viewItem.onChanged();
+    }
+  },
+
+  /**
+   * 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.
+   */
+  onDownloadRemoved(download) {
+    DownloadsCommon.log("A download data item was removed.");
+
+    let itemIndex = this._downloads.indexOf(download);
+    this._downloads.splice(itemIndex, 1);
+
+    if (itemIndex < this.kItemCountLimit) {
+      // The item to remove is visible in the panel.
+      this._removeViewItem(download);
+      if (this._downloads.length >= this.kItemCountLimit) {
+        // Reinsert the next item into the panel.
+        this._addViewItem(this._downloads[this.kItemCountLimit - 1], false);
+      }
+    }
+
+    this._itemCountChanged();
+  },
+
+  /**
+   * Associates each richlistitem for a download with its corresponding
+   * DownloadsViewItem object.
+   */
+  _itemsForElements: new Map(),
+
+  itemForElement(element) {
+    return this._itemsForElements.get(element);
+  },
+
+  /**
+   * Creates a new view item associated with the specified data item, and adds
+   * it to the top or the bottom of the list.
+   */
+  _addViewItem(download, aNewest) {
+    DownloadsCommon.log(
+      "Adding a new DownloadsViewItem to the downloads list.",
+      "aNewest =",
+      aNewest
+    );
+
+    let element = document.createXULElement("richlistitem");
+    element.setAttribute("align", "center");
+
+    let viewItem = new DownloadsViewItem(download, element);
+    this._visibleViewItems.set(download, viewItem);
+    this._itemsForElements.set(element, viewItem);
+    if (aNewest) {
+      this.richListBox.insertBefore(
+        element,
+        this.richListBox.firstElementChild
+      );
+    } else {
+      this.richListBox.appendChild(element);
+    }
+    viewItem.ensureActive();
+  },
+
+  /**
+   * Removes the view item associated with the specified data item.
+   */
+  _removeViewItem(download) {
+    DownloadsCommon.log(
+      "Removing a DownloadsViewItem from the downloads list."
+    );
+    let element = this._visibleViewItems.get(download).element;
+    let previousSelectedIndex = this.richListBox.selectedIndex;
+    this.richListBox.removeChild(element);
+    if (previousSelectedIndex != -1) {
+      this.richListBox.selectedIndex = Math.min(
+        previousSelectedIndex,
+        this.richListBox.itemCount - 1
+      );
+    }
+    this._visibleViewItems.delete(download);
+    this._itemsForElements.delete(element);
+  },
+
+  // User interface event functions
+
+  onDownloadClick(aEvent) {
+    // Handle primary clicks in the main area only:
+    if (aEvent.button == 0 && aEvent.target.closest(".downloadMainArea")) {
+      let target = aEvent.target;
+      while (target.nodeName != "richlistitem") {
+        target = target.parentNode;
+      }
+      let download = DownloadsView.itemForElement(target).download;
+      if (download.succeeded) {
+        download._launchedFromPanel = true;
+      }
+      let command = "downloadsCmd_open";
+      if (download.hasBlockedData) {
+        command = "downloadsCmd_showBlockedInfo";
+      } else if (aEvent.shiftKey || aEvent.ctrlKey || aEvent.metaKey) {
+        // We adjust the command for supported modifiers to suggest where the download
+        // may be opened
+        let openWhere = target.ownerGlobal.whereToOpenLink(aEvent, false, true);
+        if (["tab", "window", "tabshifted"].includes(openWhere)) {
+          command += ":" + openWhere;
+        }
+      }
+      // Toggle opening the file after the download has completed
+      if (
+        !download.stopped &&
+        command.startsWith("downloadsCmd_open") &&
+        Services.prefs.getBoolPref(
+          "browser.download.improvements_to_download_panel"
+        )
+      ) {
+        download.launchWhenSucceeded = !download.launchWhenSucceeded;
+        download._launchedFromPanel = download.launchWhenSucceeded;
+      }
+
+      DownloadsCommon.log("onDownloadClick, resolved command: ", command);
+      goDoCommand(command);
+    }
+  },
+
+  onDownloadButton(event) {
+    let target = event.target.closest("richlistitem");
+    DownloadsView.itemForElement(target).onButton();
+  },
+
+  /**
+   * Handles keypress events on a download item.
+   */
+  onDownloadKeyPress(aEvent) {
+    // Pressing the key on buttons should not invoke the action because the
+    // event has already been handled by the button itself.
+    if (
+      aEvent.originalTarget.hasAttribute("command") ||
+      aEvent.originalTarget.hasAttribute("oncommand")
+    ) {
+      return;
+    }
+
+    if (aEvent.charCode == " ".charCodeAt(0)) {
+      aEvent.preventDefault();
+      goDoCommand("downloadsCmd_pauseResume");
+      return;
+    }
+
+    if (aEvent.keyCode == KeyEvent.DOM_VK_RETURN) {
+      let readyToDownload = !DownloadsView.richListBox.disabled;
+      if (readyToDownload) {
+        goDoCommand("downloadsCmd_doDefault");
+      }
+    }
+  },
+
+  get contextMenu() {
+    let menu = document.getElementById("downloadsContextMenu");
+    if (menu) {
+      delete this.contextMenu;
+      this.contextMenu = menu;
+    }
+    return menu;
+  },
+
+  /**
+   * Indicates whether there is an open contextMenu for a download item.
+   */
+  get contextMenuOpen() {
+    return this.contextMenu.state != "closed";
+  },
+
+  /**
+   * Mouse listeners to handle selection on hover.
+   */
+  onDownloadMouseOver(aEvent) {
+    let item = aEvent.target.closest("richlistitem,richlistbox");
+    if (item.localName != "richlistitem") {
+      return;
+    }
+
+    if (aEvent.target.classList.contains("downloadButton")) {
+      item.classList.add("downloadHoveringButton");
+    }
+
+    item.classList.toggle(
+      "hoveringMainArea",
+      aEvent.target.closest(".downloadMainArea")
+    );
+
+    if (!this.contextMenuOpen && !this.subViewOpen) {
+      this.richListBox.selectedItem = item;
+    }
+  },
+
+  onDownloadMouseOut(aEvent) {
+    let item = aEvent.target.closest("richlistitem,richlistbox");
+    if (item.localName != "richlistitem") {
+      return;
+    }
+
+    if (aEvent.target.classList.contains("downloadButton")) {
+      item.classList.remove("downloadHoveringButton");
+    }
+
+    // If the destination element is outside of the richlistitem, clear the
+    // selection.
+    if (
+      !this.contextMenuOpen &&
+      !this.subViewOpen &&
+      !item.contains(aEvent.relatedTarget)
+    ) {
+      this.richListBox.selectedIndex = -1;
+    }
+  },
+
+  onDownloadContextMenu(aEvent) {
+    let element = this.richListBox.selectedItem;
+    if (!element) {
+      return;
+    }
+
+    DownloadsViewController.updateCommands();
+
+    DownloadsViewUI.updateContextMenuForElement(this.contextMenu, element);
+    // Hide the copy location item if there is somehow no URL. We have to do
+    // this here instead of in DownloadsViewUI because DownloadsPlacesView
+    // allows selecting multiple downloads, so in that view the menuitem will be
+    // shown according to whether at least one of the selected items has a URL.
+    this.contextMenu.querySelector(
+      ".downloadCopyLocationMenuItem"
+    ).hidden = !element._shell.download.source?.url;
+  },
+
+  onDownloadDragStart(aEvent) {
+    let element = aEvent.target.closest("richlistitem");
+    if (!element) {
+      return;
+    }
+
+    // We must check for existence synchronously because this is a DOM event.
+    let file = new FileUtils.File(
+      DownloadsView.itemForElement(element).download.target.path
+    );
+    if (!file.exists()) {
+      return;
+    }
+
+    let dataTransfer = aEvent.dataTransfer;
+    dataTransfer.mozSetDataAt("application/x-moz-file", file, 0);
+    dataTransfer.effectAllowed = "copyMove";
+    let spec = NetUtil.newURI(file).spec;
+    dataTransfer.setData("text/uri-list", spec);
+    dataTransfer.setData("text/plain", spec);
+    dataTransfer.addElement(element);
+
+    aEvent.stopPropagation();
+  },
+};
+
+XPCOMUtils.defineConstant(this, "DownloadsView", DownloadsView);
+
+// DownloadsViewItem
+
+/**
+ * Builds and updates a single item in the downloads list widget, responding to
+ * changes in the download state and real-time data, and handles the user
+ * interaction events related to a single item in the downloads list widgets.
+ *
+ * @param download
+ *        Download object to be associated with the view item.
+ * @param aElement
+ *        XUL element corresponding to the single download item in the view.
+ */
+
+class DownloadsViewItem extends DownloadsViewUI.DownloadElementShell {
+  constructor(download, aElement) {
+    super();
+
+    this.download = download;
+    this.element = aElement;
+    this.element._shell = this;
+
+    this.element.setAttribute("type", "download");
+    this.element.classList.add("download-state");
+
+    this.isPanel = true;
+  }
+
+  onChanged() {
+    let newState = DownloadsCommon.stateOfDownload(this.download);
+    if (this.downloadState !== newState) {
+      this.downloadState = newState;
+      this._updateState();
+    } else {
+      this._updateStateInner();
+    }
+  }
+
+  isCommandEnabled(aCommand) {
+    switch (aCommand) {
+      case "downloadsCmd_open":
+      case "downloadsCmd_open:current":
+      case "downloadsCmd_open:tab":
+      case "downloadsCmd_open:tabshifted":
+      case "downloadsCmd_open:window":
+      case "downloadsCmd_alwaysOpenSimilarFiles": {
+        if (!this.download.succeeded) {
+          return false;
+        }
+
+        let file = new FileUtils.File(this.download.target.path);
+        return file.exists();
+      }
+      case "downloadsCmd_show": {
+        let file = new FileUtils.File(this.download.target.path);
+        if (file.exists()) {
+          return true;
+        }
+
+        if (!this.download.target.partFilePath) {
+          return false;
+        }
+
+        let partFile = new FileUtils.File(this.download.target.partFilePath);
+        return partFile.exists();
+      }
+      case "downloadsCmd_copyLocation":
+        return !!this.download.source?.url;
+      case "cmd_delete":
+      case "downloadsCmd_doDefault":
+        return true;
+      case "downloadsCmd_showBlockedInfo":
+        return this.download.hasBlockedData;
+    }
+    return DownloadsViewUI.DownloadElementShell.prototype.isCommandEnabled.call(
+      this,
+      aCommand
+    );
+  }
+
+  doCommand(aCommand) {
+    if (this.isCommandEnabled(aCommand)) {
+      let [command, modifier] = aCommand.split(":");
+      // split off an optional command "modifier" into an argument,
+      // e.g. "downloadsCmd_open:window"
+      this[command](modifier);
+    }
+  }
+
+  // Item commands
+
+  downloadsCmd_unblock() {
+    DownloadsPanel.hidePanel();
+    this.confirmUnblock(window, "unblock");
+  }
+
+  downloadsCmd_chooseUnblock() {
+    DownloadsPanel.hidePanel();
+    this.confirmUnblock(window, "chooseUnblock");
+  }
+
+  downloadsCmd_unblockAndOpen() {
+    DownloadsPanel.hidePanel();
+    this.unblockAndOpenDownload().catch(Cu.reportError);
+  }
+  downloadsCmd_unblockAndSave() {
+    DownloadsPanel.hidePanel();
+    this.unblockAndSave();
+  }
+
+  downloadsCmd_open(openWhere) {
+    super.downloadsCmd_open(openWhere);
+
+    // We explicitly close the panel here to give the user the feedback that
+    // their click has been received, and we're handling the action.
+    // Otherwise, we'd have to wait for the file-type handler to execute
+    // before the panel would close. This also helps to prevent the user from
+    // accidentally opening a file several times.
+    DownloadsPanel.hidePanel();
+  }
+
+  downloadsCmd_openInSystemViewer() {
+    super.downloadsCmd_openInSystemViewer();
+
+    // We explicitly close the panel here to give the user the feedback that
+    // their click has been received, and we're handling the action.
+    DownloadsPanel.hidePanel();
+  }
+
+  downloadsCmd_alwaysOpenInSystemViewer() {
+    super.downloadsCmd_alwaysOpenInSystemViewer();
+
+    // We explicitly close the panel here to give the user the feedback that
+    // their click has been received, and we're handling the action.
+    DownloadsPanel.hidePanel();
+  }
+
+  downloadsCmd_alwaysOpenSimilarFiles() {
+    super.downloadsCmd_alwaysOpenSimilarFiles();
+
+    // We explicitly close the panel here to give the user the feedback that
+    // their click has been received, and we're handling the action.
+    DownloadsPanel.hidePanel();
+  }
+
+  downloadsCmd_show() {
+    let file = new FileUtils.File(this.download.target.path);
+    DownloadsCommon.showDownloadedFile(file);
+
+    // We explicitly close the panel here to give the user the feedback that
+    // their click has been received, and we're handling the action.
+    // Otherwise, we'd have to wait for the operating system file manager
+    // window to open before the panel closed. This also helps to prevent the
+    // user from opening the containing folder several times.
+    DownloadsPanel.hidePanel();
+  }
+
+  async downloadsCmd_deleteFile() {
+    await super.downloadsCmd_deleteFile();
+    // Protects against an unusual edge case where the user:
+    // 1) downloads a file with Firefox; 2) deletes the file from outside of Firefox, e.g., a file manager;
+    // 3) downloads the same file from the same source; 4) opens the downloads panel and uses the menuitem to delete one of those 2 files;
+    // Under those conditions, Firefox will make 2 view items even though there's only 1 file.
+    // Using this method will only delete the view item it was called on, because this instance is not aware of other view items with identical targets.
+    // So the remaining view item needs to be refreshed to hide the "Delete" option.
+    // That example only concerns 2 duplicate view items but you can have an arbitrary number, so iterate over all items...
+    for (let viewItem of DownloadsView._visibleViewItems.values()) {
+      viewItem.download.refresh().catch(Cu.reportError);
+    }
+    // Don't use DownloadsPanel.hidePanel for this method because it will remove
+    // the view item from the list, which is already sufficient feedback.
+  }
+
+  downloadsCmd_showBlockedInfo() {
+    DownloadsBlockedSubview.toggle(
+      this.element,
+      ...this.rawBlockedTitleAndDetails
+    );
+  }
+
+  downloadsCmd_openReferrer() {
+    openURL(this.download.source.referrerInfo.originalReferrer);
+  }
+
+  downloadsCmd_copyLocation() {
+    DownloadsCommon.copyDownloadLink(this.download);
+  }
+
+  downloadsCmd_doDefault() {
+    let defaultCommand = this.currentDefaultCommandName;
+    if (defaultCommand && this.isCommandEnabled(defaultCommand)) {
+      this.doCommand(defaultCommand);
+    }
+  }
+}
+
+// DownloadsViewController
+
+/**
+ * Handles part of the user interaction events raised by the downloads list
+ * widget, in particular the "commands" that apply to multiple items, and
+ * dispatches the commands that apply to individual items.
+ */
+var DownloadsViewController = {
+  // Initialization and termination
+
+  initialize() {
+    window.controllers.insertControllerAt(0, this);
+  },
+
+  terminate() {
+    window.controllers.removeController(this);
+  },
+
+  // nsIController
+
+  supportsCommand(aCommand) {
+    if (aCommand === "downloadsCmd_clearList") {
+      return true;
+    }
+    // Firstly, determine if this is a command that we can handle.
+    if (!DownloadsViewUI.isCommandName(aCommand)) {
+      return false;
+    }
+    // Strip off any :modifier suffix before checking if the command name is
+    // a method on our view
+    let [command] = aCommand.split(":");
+    if (!(command in this) && !(command in DownloadsViewItem.prototype)) {
+      return false;
+    }
+    // The currently supported commands depend on whether the blocked subview is
+    // showing.  If it is, then take the following path.
+    if (DownloadsView.subViewOpen) {
+      let blockedSubviewCmds = [
+        "downloadsCmd_unblockAndOpen",
+        "cmd_delete",
+        "downloadsCmd_unblockAndSave",
+      ];
+      return blockedSubviewCmds.includes(aCommand);
+    }
+    // If the blocked subview is not showing, then determine if focus is on a
+    // control in the downloads list.
+    let element = document.commandDispatcher.focusedElement;
+    while (element && element != DownloadsView.richListBox) {
+      element = element.parentNode;
+    }
+    // We should handle the command only if the downloads list is among the
+    // ancestors of the focused element.
+    return !!element;
+  },
+
+  isCommandEnabled(aCommand) {
+    // Handle commands that are not selection-specific.
+    if (aCommand == "downloadsCmd_clearList") {
+      return DownloadsCommon.getData(window).canRemoveFinished;
+    }
+
+    // Other commands are selection-specific.
+    let element = DownloadsView.richListBox.selectedItem;
+    return (
+      element &&
+      DownloadsView.itemForElement(element).isCommandEnabled(aCommand)
+    );
+  },
+
+  doCommand(aCommand) {
+    // If this command is not selection-specific, execute it.
+    if (aCommand in this) {
+      this[aCommand]();
+      return;
+    }
+
+    // Other commands are selection-specific.
+    let element = DownloadsView.richListBox.selectedItem;
+    if (element) {
+      // The doCommand function also checks if the command is enabled.
+      DownloadsView.itemForElement(element).doCommand(aCommand);
+    }
+  },
+
+  onEvent() {},
+
+  // Other functions
+
+  updateCommands() {
+    function updateCommandsForObject(object) {
+      for (let name in object) {
+        if (DownloadsViewUI.isCommandName(name)) {
+          goUpdateCommand(name);
+        }
+      }
+    }
+    updateCommandsForObject(this);
+    updateCommandsForObject(DownloadsViewItem.prototype);
+  },
+
+  // Selection-independent commands
+
+  downloadsCmd_clearList() {
+    DownloadsCommon.getData(window).removeFinished();
+  },
+};
+
+XPCOMUtils.defineConstant(
+  this,
+  "DownloadsViewController",
+  DownloadsViewController
+);
+
+// DownloadsSummary
+
+/**
+ * Manages the summary at the bottom of the downloads panel list if the number
+ * of items in the list exceeds the panels limit.
+ */
+var DownloadsSummary = {
+  /**
+   * Sets the active state of the summary. When active, the summary subscribes
+   * to the DownloadsCommon DownloadsSummaryData singleton.
+   *
+   * @param aActive
+   *        Set to true to activate the summary.
+   */
+  set active(aActive) {
+    if (aActive == this._active || !this._summaryNode) {
+      return;
+    }
+    if (aActive) {
+      DownloadsCommon.getSummary(
+        window,
+        DownloadsView.kItemCountLimit
+      ).refreshView(this);
+    } else {
+      DownloadsFooter.showingSummary = false;
+    }
+
+    this._active = aActive;
+  },
+
+  /**
+   * Returns the active state of the downloads summary.
+   */
+  get active() {
+    return this._active;
+  },
+
+  _active: false,
+
+  /**
+   * Sets whether or not we show the progress bar.
+   *
+   * @param aShowingProgress
+   *        True if we should show the progress bar.
+   */
+  set showingProgress(aShowingProgress) {
+    if (aShowingProgress) {
+      this._summaryNode.setAttribute("inprogress", "true");
+    } else {
+      this._summaryNode.removeAttribute("inprogress");
+    }
+    // If progress isn't being shown, then we simply do not show the summary.
+    DownloadsFooter.showingSummary = aShowingProgress;
+  },
+
+  /**
+   * Sets the amount of progress that is visible in the progress bar.
+   *
+   * @param aValue
+   *        A value between 0 and 100 to represent the progress of the
+   *        summarized downloads.
+   */
+  set percentComplete(aValue) {
+    if (this._progressNode) {
+      this._progressNode.setAttribute("value", aValue);
+    }
+  },
+
+  /**
+   * Sets the description for the download summary.
+   *
+   * @param aValue
+   *        A string representing the description of the summarized
+   *        downloads.
+   */
+  set description(aValue) {
+    if (this._descriptionNode) {
+      this._descriptionNode.setAttribute("value", aValue);
+      this._descriptionNode.setAttribute("tooltiptext", aValue);
+    }
+  },
+
+  /**
+   * Sets the details for the download summary, such as the time remaining,
+   * the amount of bytes transferred, etc.
+   *
+   * @param aValue
+   *        A string representing the details of the summarized
+   *        downloads.
+   */
+  set details(aValue) {
+    if (this._detailsNode) {
+      this._detailsNode.setAttribute("value", aValue);
+      this._detailsNode.setAttribute("tooltiptext", aValue);
+    }
+  },
+
+  /**
+   * Focuses the root element of the summary.
+   */
+  focus(focusOptions) {
+    if (this._summaryNode) {
+      this._summaryNode.focus(focusOptions);
+    }
+  },
+
+  /**
+   * Respond to keydown events on the Downloads Summary node.
+   *
+   * @param aEvent
+   *        The keydown event being handled.
+   */
+  onKeyDown(aEvent) {
+    if (
+      aEvent.charCode == " ".charCodeAt(0) ||
+      aEvent.keyCode == KeyEvent.DOM_VK_RETURN
+    ) {
+      DownloadsPanel.showDownloadsHistory();
+    }
+  },
+
+  /**
+   * Respond to click events on the Downloads Summary node.
+   *
+   * @param aEvent
+   *        The click event being handled.
+   */
+  onClick(aEvent) {
+    DownloadsPanel.showDownloadsHistory();
+  },
+
+  /**
+   * Element corresponding to the root of the downloads summary.
+   */
+  get _summaryNode() {
+    let node = document.getElementById("downloadsSummary");
+    if (!node) {
+      return null;
+    }
+    delete this._summaryNode;
+    return (this._summaryNode = node);
+  },
+
+  /**
+   * Element corresponding to the progress bar in the downloads summary.
+   */
+  get _progressNode() {
+    let node = document.getElementById("downloadsSummaryProgress");
+    if (!node) {
+      return null;
+    }
+    delete this._progressNode;
+    return (this._progressNode = node);
+  },
+
+  /**
+   * Element corresponding to the main description of the downloads
+   * summary.
+   */
+  get _descriptionNode() {
+    let node = document.getElementById("downloadsSummaryDescription");
+    if (!node) {
+      return null;
+    }
+    delete this._descriptionNode;
+    return (this._descriptionNode = node);
+  },
+
+  /**
+   * Element corresponding to the secondary description of the downloads
+   * summary.
+   */
+  get _detailsNode() {
+    let node = document.getElementById("downloadsSummaryDetails");
+    if (!node) {
+      return null;
+    }
+    delete this._detailsNode;
+    return (this._detailsNode = node);
+  },
+};
+
+XPCOMUtils.defineConstant(this, "DownloadsSummary", DownloadsSummary);
+
+// DownloadsFooter
+
+/**
+ * Manages events sent to to the footer vbox, which contains both the
+ * DownloadsSummary as well as the "Show all downloads" button.
+ */
+var DownloadsFooter = {
+  /**
+   * Focuses the appropriate element within the footer. If the summary
+   * is visible, focus it. If not, focus the "Show all downloads"
+   * button.
+   */
+  focus(focusOptions) {
+    if (this._showingSummary) {
+      DownloadsSummary.focus(focusOptions);
+    } else {
+      DownloadsView.downloadsHistory.focus(focusOptions);
+    }
+  },
+
+  _showingSummary: false,
+
+  /**
+   * Sets whether or not the Downloads Summary should be displayed in the
+   * footer. If not, the "Show all downloads" button is shown instead.
+   */
+  set showingSummary(aValue) {
+    if (this._footerNode) {
+      if (aValue) {
+        this._footerNode.setAttribute("showingsummary", "true");
+      } else {
+        this._footerNode.removeAttribute("showingsummary");
+      }
+      this._showingSummary = aValue;
+    }
+  },
+
+  /**
+   * Element corresponding to the footer of the downloads panel.
+   */
+  get _footerNode() {
+    let node = document.getElementById("downloadsFooter");
+    if (!node) {
+      return null;
+    }
+    delete this._footerNode;
+    return (this._footerNode = node);
+  },
+};
+
+XPCOMUtils.defineConstant(this, "DownloadsFooter", DownloadsFooter);
+
+// DownloadsBlockedSubview
+
+/**
+ * Manages the blocked subview that slides in when you click a blocked download.
+ */
+var DownloadsBlockedSubview = {
+  /**
+   * Elements in the subview.
+   */
+  get elements() {
+    let idSuffixes = [
+      "title",
+      "details1",
+      "details2",
+      "unblockButton",
+      "deleteButton",
+    ];
+    let elements = idSuffixes.reduce((memo, s) => {
+      memo[s] = document.getElementById("downloadsPanel-blockedSubview-" + s);
+      return memo;
+    }, {});
+    delete this.elements;
+    return (this.elements = elements);
+  },
+
+  /**
+   * The blocked-download richlistitem element that was clicked to show the
+   * subview.  If the subview is not showing, this is undefined.
+   */
+  element: undefined,
+
+  /**
+   * Slides in the blocked subview.
+   *
+   * @param element
+   *        The blocked-download richlistitem element that was clicked.
+   * @param title
+   *        The title to show in the subview.
+   * @param details
+   *        An array of strings with information about the block.
+   */
+  toggle(element, title, details) {
+    DownloadsView.subViewOpen = true;
+    DownloadsViewController.updateCommands();
+    const { download } = DownloadsView.itemForElement(element);
+
+    let e = this.elements;
+    let s = DownloadsCommon.strings;
+
+    title.l10n
+      ? document.l10n.setAttributes(e.title, title.l10n.id, title.l10n.args)
+      : (e.title.textContent = title);
+
+    details[0].l10n
+      ? document.l10n.setAttributes(
+          e.details1,
+          details[0].l10n.id,
+          details[0].l10n.args
+        )
+      : (e.details1.textContent = details[0]);
+
+    e.details2.textContent = details[1];
+
+    if (download.launchWhenSucceeded) {
+      e.unblockButton.label = s.unblockButtonOpen;
+      e.unblockButton.command = "downloadsCmd_unblockAndOpen";
+    } else {
+      e.unblockButton.label = s.unblockButtonUnblock;
+      e.unblockButton.command = "downloadsCmd_unblockAndSave";
+    }
+
+    e.deleteButton.label = s.unblockButtonConfirmBlock;
+
+    let verdict = element.getAttribute("verdict");
+    this.subview.setAttribute("verdict", verdict);
+
+    this.mainView.addEventListener("ViewShown", this);
+    DownloadsPanel.panel.addEventListener("popuphidden", this);
+    this.panelMultiView.showSubView(this.subview);
+
+    // Without this, the mainView is more narrow than the panel once all
+    // downloads are removed from the panel.
+    this.mainView.style.minWidth = window.getComputedStyle(this.subview).width;
+  },
+
+  handleEvent(event) {
+    // This is called when the main view is shown or the panel is hidden.
+    DownloadsView.subViewOpen = false;
+    this.mainView.removeEventListener("ViewShown", this);
+    DownloadsPanel.panel.removeEventListener("popuphidden", this);
+    // Focus the proper element if we're going back to the main panel.
+    if (event.type == "ViewShown") {
+      DownloadsPanel.showPanel();
+    }
+  },
+
+  /**
+   * Deletes the download and hides the entire panel.
+   */
+  confirmBlock() {
+    goDoCommand("cmd_delete");
+    DownloadsPanel.hidePanel();
+  },
+};
+
+XPCOMUtils.defineLazyGetter(DownloadsBlockedSubview, "panelMultiView", () =>
+  document.getElementById("downloadsPanel-multiView")
+);
+XPCOMUtils.defineLazyGetter(DownloadsBlockedSubview, "mainView", () =>
+  document.getElementById("downloadsPanel-mainView")
+);
+XPCOMUtils.defineLazyGetter(DownloadsBlockedSubview, "subview", () =>
+  document.getElementById("downloadsPanel-blockedSubview")
+);
+
+XPCOMUtils.defineConstant(
+  this,
+  "DownloadsBlockedSubview",
+  DownloadsBlockedSubview
+);