Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

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

10 files changed, 5166 insertions, 0 deletions

diff --git a/comm/suite/components/sessionstore/XPathGenerator.jsm b/comm/suite/components/sessionstore/XPathGenerator.jsm
new file mode 100644
index 0000000000..e202468a27
--- /dev/null
+++ b/comm/suite/components/sessionstore/XPathGenerator.jsm
@@ -0,0 +1,97 @@
+/* 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/. */
+
+var EXPORTED_SYMBOLS = ["XPathGenerator"];
+
+var XPathGenerator = {
+  // these two hashes should be kept in sync
+  namespaceURIs:     { "xhtml": "http://www.w3.org/1999/xhtml" },
+  namespacePrefixes: { "http://www.w3.org/1999/xhtml": "xhtml" },
+
+  /**
+   * Generates an approximate XPath query to an (X)HTML node
+   */
+  generate: function sss_xph_generate(aNode) {
+    // have we reached the document node already?
+    if (!aNode.parentNode)
+      return "";
+
+    // Access localName, namespaceURI just once per node since it's expensive.
+    let nNamespaceURI = aNode.namespaceURI;
+    let nLocalName = aNode.localName;
+
+    let prefix = this.namespacePrefixes[nNamespaceURI] || null;
+    let tag = (prefix ? prefix + ":" : "") + this.escapeName(nLocalName);
+
+    // stop once we've found a tag with an ID
+    if (aNode.id)
+      return "//" + tag + "[@id=" + this.quoteArgument(aNode.id) + "]";
+
+    // count the number of previous sibling nodes of the same tag
+    // (and possible also the same name)
+    let count = 0;
+    let nName = aNode.name || null;
+    for (let n = aNode; (n = n.previousSibling); )
+      if (n.localName == nLocalName && n.namespaceURI == nNamespaceURI &&
+          (!nName || n.name == nName))
+        count++;
+
+    // recurse until hitting either the document node or an ID'd node
+    return this.generate(aNode.parentNode) + "/" + tag +
+           (nName ? "[@name=" + this.quoteArgument(nName) + "]" : "") +
+           (count ? "[" + (count + 1) + "]" : "");
+  },
+
+  /**
+   * Resolves an XPath query generated by XPathGenerator.generate
+   */
+  resolve: function sss_xph_resolve(aDocument, aQuery) {
+    let xptype = aDocument.defaultView.XPathResult.FIRST_ORDERED_NODE_TYPE;
+    return aDocument.evaluate(aQuery, aDocument, this.resolveNS, xptype, null).singleNodeValue;
+  },
+
+  /**
+   * Namespace resolver for the above XPath resolver
+   */
+  resolveNS: function sss_xph_resolveNS(aPrefix) {
+    return XPathGenerator.namespaceURIs[aPrefix] || null;
+  },
+
+  /**
+   * @returns valid XPath for the given node (usually just the local name itself)
+   */
+  escapeName: function sss_xph_escapeName(aName) {
+    // we can't just use the node's local name, if it contains
+    // special characters (cf. bug 485482)
+    return /^\w+$/.test(aName) ? aName :
+           "*[local-name()=" + this.quoteArgument(aName) + "]";
+  },
+
+  /**
+   * @returns a properly quoted string to insert into an XPath query
+   */
+  quoteArgument: function sss_xph_quoteArgument(aArg) {
+    return !/'/.test(aArg) ? "'" + aArg + "'" :
+           !/"/.test(aArg) ? '"' + aArg + '"' :
+           "concat('" + aArg.replace(/'+/g, "',\"$&\",'") + "')";
+  },
+
+  /**
+   * @returns an XPath query to all savable form field nodes
+   */
+  get restorableFormNodes() {
+    // for a comprehensive list of all available <INPUT> types see
+    // http://mxr.mozilla.org/mozilla-central/search?string=kInputTypeTable
+    let ignoreTypes = ["password", "hidden", "button", "image", "submit", "reset"];
+    // XXXzeniko work-around until lower-case has been implemented (bug 398389)
+    let toLowerCase = '"ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghijklmnopqrstuvwxyz"';
+    let ignore = "not(translate(@type, " + toLowerCase + ")='" +
+      ignoreTypes.join("' or translate(@type, " + toLowerCase + ")='") + "')";
+    let formNodesXPath = "//textarea|//select|//xhtml:textarea|//xhtml:select|" +
+      "//input[" + ignore + "]|//xhtml:input[" + ignore + "]";
+
+    delete this.restorableFormNodes;
+    return (this.restorableFormNodes = formNodesXPath);
+  }
+};
diff --git a/comm/suite/components/sessionstore/content/aboutSessionRestore.js b/comm/suite/components/sessionstore/content/aboutSessionRestore.js
new file mode 100644
index 0000000000..677bf20adc
--- /dev/null
+++ b/comm/suite/components/sessionstore/content/aboutSessionRestore.js
@@ -0,0 +1,291 @@
+/* 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/. */
+
+var {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+var gStateObject;
+var gTreeData;
+
+// Page initialization
+
+window.onload = function() {
+  // establish the event handlers for <tree> and <button> elements
+  var tabList = document.getElementById("tabList");
+  tabList.addEventListener("click", onListClick);
+  tabList.addEventListener("keydown", onListKeyDown);
+
+  document.getElementById("errorTryAgain")
+          .addEventListener("command", restoreSession);
+
+  document.getElementById("errorCancel")
+          .addEventListener("command", startNewSession);
+
+  // the crashed session state is kept inside a textbox so that SessionStore picks it up
+  // (for when the tab is closed or the session crashes right again)
+  var sessionData = document.getElementById("sessionData");
+  if (!sessionData.value) {
+    var ss = Cc["@mozilla.org/suite/sessionstartup;1"].getService(Ci.nsISessionStartup);
+    sessionData.value = ss.state;
+    if (!sessionData.value) {
+      document.getElementById("errorTryAgain").disabled = true;
+      return;
+    }
+  }
+  // make sure the data is tracked to be restored in case of a subsequent crash
+  sessionData.dispatchEvent(new UIEvent("input",
+    { bubbles: true, cancelable: true, view: window, detail: 0 }));
+
+  gStateObject = JSON.parse(sessionData.value);
+
+  initTreeView();
+
+  document.getElementById("errorTryAgain").focus();
+};
+
+function initTreeView() {
+  var tabList = document.getElementById("tabList");
+  var winLabel = tabList.getAttribute("_window_label");
+
+  gTreeData = [];
+  gStateObject.windows.forEach(function(aWinData, aIx) {
+    var winState = {
+      label: winLabel.replace("%S", (aIx + 1)),
+      open: true,
+      checked: true,
+      ix: aIx
+    };
+    winState.tabs = aWinData.tabs.map(function(aTabData) {
+      var entry = aTabData.entries[aTabData.index - 1] || { url: "about:blank" };
+      var iconURL = aTabData.attributes && aTabData.attributes.image || null;
+      // don't initiate a connection just to fetch a favicon (see bug 462863)
+      if (/^https?:/.test(iconURL))
+        iconURL = "moz-anno:favicon:" + iconURL;
+      return {
+        label: entry.title || entry.url,
+        checked: true,
+        src: iconURL,
+        parent: winState
+      };
+    });
+    gTreeData.push(winState);
+    for (var tab of winState.tabs)
+      gTreeData.push(tab);
+  }, this);
+
+  tabList.view = treeView;
+  tabList.view.selection.select(0);
+}
+
+// User actions
+
+function restoreSession() {
+  document.getElementById("errorTryAgain").disabled = true;
+
+  // remove all unselected tabs from the state before restoring it
+  var ix = gStateObject.windows.length - 1;
+  for (var t = gTreeData.length - 1; t >= 0; t--) {
+    if (treeView.isContainer(t)) {
+      if (gTreeData[t].checked === 0)
+        // this window will be restored partially
+        gStateObject.windows[ix].tabs =
+          gStateObject.windows[ix].tabs.filter((aTabData, aIx) =>
+                                                 gTreeData[t].tabs[aIx].checked);
+      else if (!gTreeData[t].checked)
+        // this window won't be restored at all
+        gStateObject.windows.splice(ix, 1);
+      ix--;
+    }
+  }
+  var stateString = JSON.stringify(gStateObject);
+
+  var ss = Cc["@mozilla.org/suite/sessionstore;1"].getService(Ci.nsISessionStore);
+  var top = getBrowserWindow();
+
+  // if there's only this page open, reuse the window for restoring the session
+  if (top.gBrowser.tabContainer.childNodes.length == 1) {
+    ss.setWindowState(top, stateString, true);
+    return;
+  }
+
+  // restore the session into a new window and close the current tab
+  var newWindow = top.openDialog(top.location, "_blank", "chrome,dialog=no,all", "about:blank");
+  var tab = top.gBrowser.selectedTab;
+  newWindow.addEventListener("load", function newWindowLoad() {
+    newWindow.removeEventListener("load", newWindowLoad, true);
+    ss.setWindowState(newWindow, stateString, true);
+
+    top.gBrowser.removeTab(tab);
+  }, true);
+}
+
+function startNewSession() {
+  if (Services.prefs.getIntPref("browser.startup.page") == 1)
+    getBrowserWindow().BrowserHome();
+  else
+    getBrowserWindow().getBrowser().loadURI("about:blank");
+}
+
+function onListClick(aEvent) {
+  // don't react to right-clicks
+  if (aEvent.button == 2)
+    return;
+
+  var cell = treeView.treeBox.getCellAt(aEvent.clientX, aEvent.clientY);
+  if (cell.col) {
+    // restore this specific tab in the same window for middle-clicking
+    // or Ctrl+clicking on a tab's title
+    if ((aEvent.button == 1 || aEvent.ctrlKey) && cell.col.id == "title" &&
+        !treeView.isContainer(cell.row))
+      restoreSingleTab(cell.row, aEvent.shiftKey);
+    else if (cell.col.id == "restore")
+      toggleRowChecked(cell.row);
+  }
+}
+
+function onListKeyDown(aEvent) {
+  switch (aEvent.keyCode)
+  {
+  case KeyEvent.DOM_VK_SPACE:
+    toggleRowChecked(document.getElementById("tabList").currentIndex);
+    break;
+  case KeyEvent.DOM_VK_RETURN:
+    var ix = document.getElementById("tabList").currentIndex;
+    if (aEvent.ctrlKey && !treeView.isContainer(ix))
+      restoreSingleTab(ix, aEvent.shiftKey);
+    break;
+  }
+}
+
+// Helper functions
+
+function getBrowserWindow() {
+  return window.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIWebNavigation)
+               .QueryInterface(Ci.nsIDocShellTreeItem).rootTreeItem
+               .QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindow);
+}
+
+function toggleRowChecked(aIx) {
+  var item = gTreeData[aIx];
+  item.checked = !item.checked;
+  treeView.treeBox.invalidateRow(aIx);
+
+  function isChecked(aItem) {
+    return aItem.checked;
+  }
+
+  if (treeView.isContainer(aIx)) {
+    // (un)check all tabs of this window as well
+    for (var tab of item.tabs) {
+      tab.checked = item.checked;
+      treeView.treeBox.invalidateRow(gTreeData.indexOf(tab));
+    }
+  }
+  else {
+    // update the window's checkmark as well (0 means "partially checked")
+    item.parent.checked = item.parent.tabs.every(isChecked) ? true :
+                          item.parent.tabs.some(isChecked) ? 0 : false;
+    treeView.treeBox.invalidateRow(gTreeData.indexOf(item.parent));
+  }
+
+  document.getElementById("errorTryAgain").disabled = !gTreeData.some(isChecked);
+}
+
+function restoreSingleTab(aIx, aShifted) {
+  var tabbrowser = getBrowserWindow().gBrowser;
+  var newTab = tabbrowser.addTab();
+  var item = gTreeData[aIx];
+
+  var ss = Cc["@mozilla.org/suite/sessionstore;1"].getService(Ci.nsISessionStore);
+  var tabState = gStateObject.windows[item.parent.ix]
+                             .tabs[aIx - gTreeData.indexOf(item.parent) - 1];
+  ss.setTabState(newTab, JSON.stringify(tabState));
+
+  // respect the preference as to whether to select the tab (the Shift key inverses)
+  if (Services.prefs.getBoolPref("browser.tabs.loadInBackground") != !aShifted)
+    tabbrowser.selectedTab = newTab;
+}
+
+// Tree controller
+
+var treeView = {
+  treeBox: null,
+  selection: null,
+
+  get rowCount()                     { return gTreeData.length; },
+  setTree: function(treeBox)         { this.treeBox = treeBox; },
+  getCellText: function(idx, column) { return gTreeData[idx].label; },
+  isContainer: function(idx)         { return "open" in gTreeData[idx]; },
+  getCellValue: function(idx, column){ return gTreeData[idx].checked; },
+  isContainerOpen: function(idx)     { return gTreeData[idx].open; },
+  isContainerEmpty: function(idx)    { return false; },
+  isSeparator: function(idx)         { return false; },
+  isSorted: function()               { return false; },
+  isEditable: function(idx, column)  { return false; },
+  canDrop: function(idx, orientation, dt)  { return false; },
+  getLevel: function(idx)            { return this.isContainer(idx) ? 0 : 1; },
+
+  getParentIndex: function(idx) {
+    if (!this.isContainer(idx))
+      for (var t = idx - 1; t >= 0 ; t--)
+        if (this.isContainer(t))
+          return t;
+    return -1;
+  },
+
+  hasNextSibling: function(idx, after) {
+    var thisLevel = this.getLevel(idx);
+    for (var t = after + 1; t < gTreeData.length; t++)
+      if (this.getLevel(t) <= thisLevel)
+        return this.getLevel(t) == thisLevel;
+    return false;
+  },
+
+  toggleOpenState: function(idx) {
+    if (!this.isContainer(idx))
+      return;
+    var item = gTreeData[idx];
+    if (item.open) {
+      // remove this window's tab rows from the view
+      var thisLevel = this.getLevel(idx);
+      for (var t = idx + 1; t < gTreeData.length && this.getLevel(t) > thisLevel; t++);
+      var deletecount = t - idx - 1;
+      gTreeData.splice(idx + 1, deletecount);
+      this.treeBox.rowCountChanged(idx + 1, -deletecount);
+    }
+    else {
+      // add this window's tab rows to the view
+      var toinsert = gTreeData[idx].tabs;
+      for (var i = 0; i < toinsert.length; i++)
+        gTreeData.splice(idx + i + 1, 0, toinsert[i]);
+      this.treeBox.rowCountChanged(idx + 1, toinsert.length);
+    }
+    item.open = !item.open;
+    this.treeBox.invalidateRow(idx);
+  },
+
+  getCellProperties: function(idx, column) {
+    if (column.id == "restore" && this.isContainer(idx) && gTreeData[idx].checked === 0)
+      return "partial";
+    if (column.id == "title")
+      return this.getImageSrc(idx, column) ? "icon" : "noicon";
+    return "";
+  },
+
+  getRowProperties: function(idx) {
+    var winState = gTreeData[idx].parent || gTreeData[idx];
+    return winState.ix % 2 != 0 ? "alternate" : "";
+  },
+
+  getImageSrc: function(idx, column) {
+    if (column.id == "title")
+      return gTreeData[idx].src || null;
+    return null;
+  },
+
+  getProgressMode : function(idx, column) { },
+  cycleHeader: function(column) { },
+  cycleCell: function(idx, column) { },
+  selectionChanged: function() { },
+  getColumnProperties: function(column) { return ""; }
+};
diff --git a/comm/suite/components/sessionstore/content/aboutSessionRestore.xhtml b/comm/suite/components/sessionstore/content/aboutSessionRestore.xhtml
new file mode 100644
index 0000000000..34c9a893ea
--- /dev/null
+++ b/comm/suite/components/sessionstore/content/aboutSessionRestore.xhtml
@@ -0,0 +1,84 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+# 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/.
+-->
+<!DOCTYPE html [
+<!ENTITY % brandDTD SYSTEM "chrome://branding/locale/brand.dtd" >
+  %brandDTD;
+  <!ENTITY % htmlDTD PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd">
+  %htmlDTD;
+  <!ENTITY % netErrorDTD SYSTEM "chrome://global/locale/netError.dtd">
+  %netErrorDTD;
+  <!ENTITY % globalDTD SYSTEM "chrome://global/locale/global.dtd">
+  %globalDTD;
+  <!ENTITY % restorepageDTD SYSTEM "chrome://communicator/locale/aboutSessionRestore.dtd">
+  %restorepageDTD;
+]>
+
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <title>&restorepage.tabtitle;</title>
+    <link rel="stylesheet" href="chrome://global/skin/netError.css" type="text/css" media="all"/>
+    <link rel="stylesheet" href="chrome://communicator/skin/aboutSessionRestore.css" type="text/css" media="all"/>
+    <link rel="icon" type="image/png" href="chrome://global/skin/icons/question-16.png"/>
+
+    <script src="chrome://communicator/content/aboutSessionRestore.js"/>
+  </head>
+
+  <body dir="&locale.dir;">
+
+    <!-- PAGE CONTAINER (for styling purposes only) -->
+    <div id="errorPageContainer">
+
+      <!-- Error Title -->
+      <div id="errorTitle">
+        <h1 id="errorTitleText">&restorepage.pagetitle;</h1>
+      </div>
+
+      <!-- LONG CONTENT (the section most likely to require scrolling) -->
+      <div id="errorLongContent">
+
+        <!-- Short Description -->
+        <div id="errorShortDesc">
+          <p id="errorShortDescText">&restorepage.issueDesc;</p>
+        </div>
+
+        <!-- Long Description (Note: See netError.dtd for used XHTML tags) -->
+        <div id="errorLongDesc">
+          <p>&restorepage.remedies;</p>
+          <ul>
+            <li>&restorepage.dueToChrome;</li>
+            <li>&restorepage.dueToContent;</li>
+          </ul>
+        </div>
+
+        <!-- Short Description -->
+        <div id="errorTrailerDesc">
+          <tree xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+                id="tabList" flex="1" seltype="single" hidecolumnpicker="true"
+                _window_label="&restorepage.windowLabel;">
+            <treecols>
+              <treecol id="restore" type="checkbox" label="&restorepage.restoreHeader;"/>
+              <splitter class="tree-splitter"/>
+              <treecol primary="true" id="title" label="&restorepage.listHeader;" flex="1"/>
+            </treecols>
+            <treechildren flex="1"/>
+          </tree>
+        </div>
+      </div>
+
+      <!-- Buttons -->
+      <hbox xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" id="buttons">
+        <button id="errorTryAgain" label="&restorepage.restoreButton;"
+                accesskey="&restorepage.restore.access;"/>
+        <button id="errorCancel" label="&restorepage.cancelButton;"
+                accesskey="&restorepage.cancel.access;"/>
+      </hbox>
+      <!-- holds the session data for when the tab is closed -->
+      <input type="hidden" id="sessionData"/>
+    </div>
+
+  </body>
+</html>
diff --git a/comm/suite/components/sessionstore/jar.mn b/comm/suite/components/sessionstore/jar.mn
new file mode 100644
index 0000000000..5a398c353e
--- /dev/null
+++ b/comm/suite/components/sessionstore/jar.mn
@@ -0,0 +1,7 @@
+# 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/.
+
+comm.jar:
+    content/communicator/aboutSessionRestore.js    (content/aboutSessionRestore.js)
+    content/communicator/aboutSessionRestore.xhtml (content/aboutSessionRestore.xhtml)
diff --git a/comm/suite/components/sessionstore/moz.build b/comm/suite/components/sessionstore/moz.build
new file mode 100644
index 0000000000..9d8fd29468
--- /dev/null
+++ b/comm/suite/components/sessionstore/moz.build
@@ -0,0 +1,24 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+XPIDL_SOURCES += [
+    "nsISessionStartup.idl",
+    "nsISessionStore.idl",
+]
+
+XPIDL_MODULE = "suitecommon"
+
+EXTRA_COMPONENTS += [
+    "nsSessionStartup.js",
+    "nsSessionStartup.manifest",
+    "nsSessionStore.js",
+]
+
+EXTRA_JS_MODULES.sessionstore = [
+    "XPathGenerator.jsm",
+]
+
+JAR_MANIFESTS += ["jar.mn"]
diff --git a/comm/suite/components/sessionstore/nsISessionStartup.idl b/comm/suite/components/sessionstore/nsISessionStartup.idl
new file mode 100644
index 0000000000..018b0c1d4c
--- /dev/null
+++ b/comm/suite/components/sessionstore/nsISessionStartup.idl
@@ -0,0 +1,39 @@
+/* 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/. */
+
+#include "nsISupports.idl"
+
+/**
+ * nsISessionStore keeps track of the current browsing state - i.e.
+ * tab history, cookies, scroll state, form data, POSTDATA and window features
+ * - and allows to restore everything into one window.
+ */
+
+[scriptable, uuid(dd709821-820a-4d0d-b7e8-a566b32377ef)]
+interface nsISessionStartup: nsISupports
+{
+  // Get session state
+  readonly attribute jsval state;
+
+  /**
+   * Determine if session should be restored
+   */
+  boolean doRestore();
+
+  /**
+   * What type of session we're restoring.
+   * NO_SESSION       There is no data available from the previous session
+   * RECOVER_SESSION  The last session crashed. It will either be restored or
+   *                  about:sessionrestore will be shown.
+   * RESUME_SESSION   The previous session should be restored at startup
+   * DEFER_SESSION    The previous session is fine, but it shouldn't be restored
+   *                  without explicit action (with the exception of pinned tabs)
+   */
+  const unsigned long NO_SESSION = 0;
+  const unsigned long RECOVER_SESSION = 1;
+  const unsigned long RESUME_SESSION = 2;
+  const unsigned long DEFER_SESSION = 3;
+
+  readonly attribute unsigned long sessionType;
+};
diff --git a/comm/suite/components/sessionstore/nsISessionStore.idl b/comm/suite/components/sessionstore/nsISessionStore.idl
new file mode 100644
index 0000000000..2fc2f22175
--- /dev/null
+++ b/comm/suite/components/sessionstore/nsISessionStore.idl
@@ -0,0 +1,216 @@
+/* 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/. */
+
+#include "nsISupports.idl"
+
+interface nsIDOMWindow;
+interface nsINode;
+
+/**
+ * nsISessionStore keeps track of the current browsing state - i.e.
+ * tab history, cookies, scroll state, form data, POSTDATA and window features
+ * - and allows to restore everything into one browser window.
+ *
+ * The nsISessionStore API operates mostly on browser windows and the tabbrowser
+ * tabs contained in them:
+ *
+ * * "Browser windows" are those DOM windows having loaded
+ * chrome://navigator/content/navigator.xul . From overlays you can just pass
+ * the global |window| object to the API, though (or |top| from a sidebar).
+ * From elsewhere you can get browser windows through the nsIWindowMediator
+ * by looking for "navigator:browser" windows.
+ *
+ * * "Tabbrowser tabs" are all the child nodes of a browser window's
+ * |getBrowser().tabContainer| such as e.g. |getBrowser().selectedTab|.
+ */
+
+[scriptable, uuid(27a8bd2b-dd76-4cee-82eb-a25f6a94478f)]
+interface nsISessionStore : nsISupports
+{
+  /**
+   * Initialize the service
+   */
+  void init(in nsIDOMWindow aWindow);
+
+  /**
+   * Is it possible to restore the previous session. Will always be false when
+   * in Private Browsing mode.
+   */
+  attribute boolean canRestoreLastSession;
+
+  /**
+   * Restore the previous session if possible. This will not overwrite the
+   * current session. Instead the previous session will be merged into the
+   * current session. Current windows will be reused if they were windows that
+   * pinned tabs were previously restored into. New windows will be opened as
+   * needed.
+   *
+   * Note: This will throw if there is no previous state to restore. Check with
+   * canRestoreLastSession first to avoid thrown errors.
+   */
+  void restoreLastSession();
+
+  /**
+   * Get the current browsing state.
+   * @returns a JSON string representing the session state.
+   */
+  AString getBrowserState();
+
+  /**
+   * Set the browsing state.
+   * This will immediately restore the state of the whole application to the state
+   * passed in, *replacing* the current session.
+   *
+   * @param aState is a JSON string representing the session state.
+   */
+  void setBrowserState(in AString aState);
+
+  /**
+   * @param aWindow is the browser window whose state is to be returned.
+   *
+   * @returns a JSON string representing a session state with only one window.
+   */
+  AString getWindowState(in nsIDOMWindow aWindow);
+
+  /**
+   * @param aWindow    is the browser window whose state is to be set.
+   * @param aState     is a JSON string representing a session state.
+   * @param aOverwrite boolean overwrite existing tabs
+   */
+  void setWindowState(in nsIDOMWindow aWindow, in AString aState, in boolean aOverwrite);
+
+  /**
+   * @param aTab is the tabbrowser tab whose state is to be returned.
+   *
+   * @returns a JSON string representing the state of the tab
+   *         (note: doesn't contain cookies - if you need them, use getWindowState instead).
+   */
+  AString getTabState(in nsINode aTab);
+
+  /**
+   * @param aTab   is the tabbrowser tab whose state is to be set.
+   * @param aState is a JSON string representing a session state.
+   */
+  void setTabState(in nsINode aTab, in AString aState);
+
+  /**
+   * Duplicates a given tab as thoroughly as possible.
+   *
+   * @param aWindow  is the browser window into which the tab will be duplicated.
+   *                 Pass null if you want to create a new window.
+   * @param aTab     is the tabbrowser tab to duplicate (can be from a different window).
+   * @param aDelta   is the offset to the history entry that you want to load.
+   * @param aRelated is a flag to be passed to addTab().
+   * @returns a reference to the newly created tab, or null if opening a window.
+   */
+  nsINode duplicateTab(in nsIDOMWindow aWindow, in nsINode aTab,
+                          [optional] in long aDelta,
+                          [optional] in boolean aRelated);
+
+  /**
+   * Get the number of restore-able tabs for a browser window
+   */
+  unsigned long getClosedTabCount(in nsIDOMWindow aWindow);
+
+  /**
+   * Get closed tab data
+   *
+   * @param aWindow is the browser window for which to get closed tab data
+   * @returns a JSON string representing the list of closed tabs.
+   */
+  AString getClosedTabData(in nsIDOMWindow aWindow);
+
+  /**
+   * @param aWindow is the browser window to reopen a closed tab in.
+   * @param aIndex  is the index of the tab to be restored (FIFO ordered).
+   * @returns a reference to the reopened tab.
+   */
+  nsINode undoCloseTab(in nsIDOMWindow aWindow, in unsigned long aIndex);
+
+  /**
+   * @param aWindow is the browser window associated with the closed tab.
+   * @param aIndex  is the index of the closed tab to be removed (FIFO ordered).
+   */
+  nsINode forgetClosedTab(in nsIDOMWindow aWindow, in unsigned long aIndex);
+
+  /**
+   * Get the number of restore-able windows
+   */
+  unsigned long getClosedWindowCount();
+
+  /**
+   * Get closed windows data
+   *
+   * @returns a JSON string representing the list of closed windows.
+   */
+  AString getClosedWindowData();
+
+  /**
+   * @param aIndex is the index of the windows to be restored (FIFO ordered).
+   * @returns the nsIDOMWindow object of the reopened window
+   */
+  nsIDOMWindow undoCloseWindow(in unsigned long aIndex);
+
+  /**
+   * @param aIndex  is the index of the closed window to be removed (FIFO ordered).
+   *
+   * @throws NS_ERROR_INVALID_ARG
+   *   when aIndex does not map to a closed window
+   */
+  nsINode forgetClosedWindow(in unsigned long aIndex);
+
+  /**
+   * @param aWindow is the window to get the value for.
+   * @param aKey    is the value's name.
+   *
+   * @returns A string value or an empty string if none is set.
+   */
+  AString getWindowValue(in nsIDOMWindow aWindow, in AString aKey);
+
+  /**
+   * @param aWindow      is the browser window to set the value for.
+   * @param aKey         is the value's name.
+   * @param aStringValue is the value itself (use toSource/eval before setting JS objects).
+   */
+  void setWindowValue(in nsIDOMWindow aWindow, in AString aKey, in AString aStringValue);
+
+  /**
+   * @param aWindow is the browser window to get the value for.
+   * @param aKey    is the value's name.
+   */
+  void deleteWindowValue(in nsIDOMWindow aWindow, in AString aKey);
+
+  /**
+   * @param aTab is the tabbrowser tab to get the value for.
+   * @param aKey is the value's name.
+   *
+   * @returns A string value or an empty string if none is set.
+   */
+  AString getTabValue(in nsINode aTab, in AString aKey);
+
+  /**
+   * @param aTab         is the tabbrowser tab to set the value for.
+   * @param aKey         is the value's name.
+   * @param aStringValue is the value itself (use toSource/eval before setting JS objects).
+   */
+  void setTabValue(in nsINode aTab, in AString aKey, in AString aStringValue);
+
+  /**
+   * @param aTab is the tabbrowser tab to get the value for.
+   * @param aKey is the value's name.
+   */
+  void deleteTabValue(in nsINode aTab, in AString aKey);
+
+  /**
+   * @param aName is the name of the attribute to save/restore for all tabbrowser tabs.
+   */
+  void persistTabAttribute(in AString aName);
+
+  /**
+   * Returns true if the last window was closed and should be restored
+   *
+   * @returns true if the last window was closed and should be restored
+   */
+  boolean doRestoreLastWindow();
+};
diff --git a/comm/suite/components/sessionstore/nsSessionStartup.js b/comm/suite/components/sessionstore/nsSessionStartup.js
new file mode 100644
index 0000000000..32494d1f27
--- /dev/null
+++ b/comm/suite/components/sessionstore/nsSessionStartup.js
@@ -0,0 +1,223 @@
+/* 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/. */
+
+/**
+ * Session Storage and Restoration
+ *
+ * Overview
+ * This service reads user's session file at startup, and makes a determination
+ * as to whether the session should be restored. It will restore the session
+ * under the circumstances described below.
+ *
+ * Crash Detection
+ * The session file stores a session.state property, that
+ * indicates whether the browser is currently running. When the browser shuts
+ * down, the field is changed to "stopped". At startup, this field is read, and
+ * if it's value is "running", then it's assumed that the browser had previously
+ * crashed, or at the very least that something bad happened, and that we should
+ * restore the session.
+ *
+ * Forced Restarts
+ * In the event that a restart is required due to application update or extension
+ * installation, set the browser.sessionstore.resume_session_once pref to true,
+ * and the session will be restored the next time the browser starts.
+ *
+ * Always Resume
+ * This service will always resume the session if the integer pref
+ * browser.startup.page is set to 3.
+*/
+
+/* :::::::: Constants and Helpers ::::::::::::::: */
+
+var {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+var {XPCOMUtils} = ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+
+const STATE_RUNNING_STR = "running";
+
+function debug(aMsg) {
+  Services.console.logStringMessage("SessionStartup: " + aMsg);
+}
+
+/* :::::::: The Service ::::::::::::::: */
+
+function SessionStartup() {
+}
+
+SessionStartup.prototype = {
+
+  // the state to restore at startup
+  _initialState: null,
+  _sessionType: Ci.nsISessionStartup.NO_SESSION,
+
+/* ........ Global Event Handlers .............. */
+
+  /**
+   * Initialize the component
+   */
+  init: function sss_init() {
+    // get file references
+    let sessionFile = Services.dirsvc.get("ProfD", Ci.nsIFile);
+    sessionFile.append("sessionstore.json");
+
+    let doResumeSessionOnce = Services.prefs.getBoolPref("browser.sessionstore.resume_session_once");
+    let doResumeSession = doResumeSessionOnce ||
+                          Services.prefs.getIntPref("browser.startup.page") == 3;
+
+    var resumeFromCrash = Services.prefs.getBoolPref("browser.sessionstore.resume_from_crash");
+
+    // only continue if the session file exists
+    if (!sessionFile.exists())
+      return;
+
+    // get string containing session state
+    let iniString = this._readStateFile(sessionFile);
+    if (!iniString)
+      return;
+
+    try {
+      // parse the session state into JS objects
+      this._initialState = JSON.parse(iniString);
+    }
+    catch (ex) {
+      doResumeSession = false;
+      debug("The session file is invalid: " + ex);
+    }
+
+    // If this is a normal restore then throw away any previous session
+    if (!doResumeSessionOnce && this._initialState)
+      delete this._initialState.lastSessionState;
+
+    let lastSessionCrashed =
+      this._initialState && this._initialState.session &&
+      this._initialState.session.state &&
+      this._initialState.session.state == STATE_RUNNING_STR;
+
+    // set the startup type
+    if (lastSessionCrashed && resumeFromCrash)
+      this._sessionType = Ci.nsISessionStartup.RECOVER_SESSION;
+    else if (!lastSessionCrashed && doResumeSession)
+      this._sessionType = Ci.nsISessionStartup.RESUME_SESSION;
+    else if (this._initialState)
+      this._sessionType = Ci.nsISessionStartup.DEFER_SESSION;
+    else
+      this._initialState = null; // reset the state
+
+    if (this.doRestore()) {
+      // wait for the first browser window to open
+      Services.obs.addObserver(this, "sessionstore-windows-restored", true);
+    }
+  },
+
+  /**
+   * Handle notifications
+   */
+  observe: function sss_observe(aSubject, aTopic, aData) {
+    switch (aTopic) {
+    case "app-startup":
+      Services.obs.addObserver(this, "final-ui-startup", true);
+      Services.obs.addObserver(this, "quit-application", true);
+      break;
+    case "final-ui-startup":
+      Services.obs.removeObserver(this, "final-ui-startup");
+      Services.obs.removeObserver(this, "quit-application");
+      this.init();
+      break;
+    case "quit-application":
+      // no reason for initializing at this point (cf. bug 409115)
+      Services.obs.removeObserver(this, "final-ui-startup");
+      Services.obs.removeObserver(this, "quit-application");
+      break;
+    case "sessionstore-windows-restored":
+      // no need in repeating this, since session type won't change
+      Services.obs.removeObserver(this, "sessionstore-windows-restored");
+      // free _initialState after nsSessionStore is done with it
+      this._initialState = null;
+      // reset session type after restore
+      this._sessionType = Ci.nsISessionStartup.NO_SESSION;
+      break;
+    }
+  },
+
+/* ........ Public API ................*/
+
+  /**
+   * Get the session state as a string
+   */
+  get state() {
+    return this._initialState;
+  },
+
+  /**
+   * Determine whether there is a pending session restore.
+   * @returns bool
+   */
+  doRestore: function sss_doRestore() {
+    return this._sessionType == Ci.nsISessionStartup.RECOVER_SESSION ||
+           this._sessionType == Ci.nsISessionStartup.RESUME_SESSION;
+  },
+
+  /**
+   * Get the type of pending session store, if any.
+   */
+  get sessionType() {
+    return this._sessionType;
+  },
+
+/* ........ Storage API .............. */
+
+  /**
+   * Reads a session state file into a string and lets
+   * observers modify the state before it's being used
+   *
+   * @param aFile is any nsIFile
+   * @returns a session state string
+   */
+  _readStateFile: function sss_readStateFile(aFile) {
+    var stateString = Cc["@mozilla.org/supports-string;1"]
+                        .createInstance(Ci.nsISupportsString);
+    stateString.data = this._readFile(aFile) || "";
+
+    Services.obs.notifyObservers(stateString, "sessionstore-state-read");
+
+    return stateString.data;
+  },
+
+  /**
+   * reads a file into a string
+   * @param aFile
+   *        nsIFile
+   * @returns string
+   */
+  _readFile: function sss_readFile(aFile) {
+    try {
+      var stream = Cc["@mozilla.org/network/file-input-stream;1"]
+                     .createInstance(Ci.nsIFileInputStream);
+      stream.init(aFile, 0x01, 0, 0);
+      var cvStream = Cc["@mozilla.org/intl/converter-input-stream;1"]
+                       .createInstance(Ci.nsIConverterInputStream);
+      cvStream.init(stream, "UTF-8", 1024, Ci.nsIConverterInputStream.DEFAULT_REPLACEMENT_CHARACTER);
+
+      var content = "";
+      var data = {};
+      while (cvStream.readString(4096, data)) {
+        content += data.value;
+      }
+      cvStream.close();
+
+      return content.replace(/\r\n?/g, "\n");
+    }
+    catch (ex) { Cu.reportError(ex); }
+
+    return null;
+  },
+
+  /* ........ QueryInterface .............. */
+  QueryInterface : XPCOMUtils.generateQI([Ci.nsIObserver,
+                                          Ci.nsISupportsWeakReference,
+                                          Ci.nsISessionStartup]),
+  classID: Components.ID("{4e6c1112-57b6-44ba-adf9-99fb573b0a30}")
+
+};
+
+var NSGetFactory = XPCOMUtils.generateNSGetFactory([SessionStartup]);
diff --git a/comm/suite/components/sessionstore/nsSessionStartup.manifest b/comm/suite/components/sessionstore/nsSessionStartup.manifest
new file mode 100644
index 0000000000..c1ade9aa87
--- /dev/null
+++ b/comm/suite/components/sessionstore/nsSessionStartup.manifest
@@ -0,0 +1,11 @@
+# This components must restrict its registration for the app-startup category
+# to the specific list of apps that use it so it doesn't get loaded in xpcshell.
+# Thus we restrict it to these apps:
+#
+#   suite {4e6c1112-57b6-44ba-adf9-99fb573b0a30}
+
+component {4e6c1112-57b6-44ba-adf9-99fb573b0a30} nsSessionStartup.js
+contract @mozilla.org/suite/sessionstartup;1 {4e6c1112-57b6-44ba-adf9-99fb573b0a30}
+category app-startup SessionStartup service,@mozilla.org/suite/sessionstartup;1
+component {d37ccdf1-496f-4135-9575-037180af010d} nsSessionStore.js
+contract @mozilla.org/suite/sessionstore;1 {d37ccdf1-496f-4135-9575-037180af010d}
diff --git a/comm/suite/components/sessionstore/nsSessionStore.js b/comm/suite/components/sessionstore/nsSessionStore.js
new file mode 100644
index 0000000000..e469af96bb
--- /dev/null
+++ b/comm/suite/components/sessionstore/nsSessionStore.js
@@ -0,0 +1,4174 @@
+/* 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/. */
+
+/**
+ * Session Storage and Restoration
+ *
+ * Overview
+ * This service keeps track of a user's session, storing the various bits
+ * required to return the browser to its current state. The relevant data is
+ * stored in memory, and is periodically saved to disk in a file in the
+ * profile directory. The service is started at first window load, in
+ * delayedStartup, and will restore the session from the data received from
+ * the nsSessionStartup service.
+ */
+
+/* :::::::: Constants and Helpers ::::::::::::::: */
+
+const STATE_STOPPED = 0;
+const STATE_RUNNING = 1;
+const STATE_QUITTING = -1;
+
+const STATE_STOPPED_STR = "stopped";
+const STATE_RUNNING_STR = "running";
+
+const TAB_STATE_NEEDS_RESTORE = 1;
+const TAB_STATE_RESTORING = 2;
+
+const PRIVACY_NONE = 0;
+const PRIVACY_ENCRYPTED = 1;
+const PRIVACY_FULL = 2;
+
+const NOTIFY_WINDOWS_RESTORED = "sessionstore-windows-restored";
+const NOTIFY_BROWSER_STATE_RESTORED = "sessionstore-browser-state-restored";
+
+// global notifications observed
+const OBSERVING = [
+  "domwindowclosed",
+  "quit-application-requested", "quit-application-granted", "quit-application",
+  "browser-lastwindow-close-granted", "browser:purge-session-history"
+];
+
+/*
+XUL Window properties to (re)store
+Restored in restoreDimensions()
+*/
+const WINDOW_ATTRIBUTES = {
+  width: "outerWidth",
+  height: "outerHeight",
+  screenX: "screenX",
+  screenY: "screenY",
+  sizemode: "windowState"
+};
+
+/*
+Hideable window features to (re)store
+Restored in restoreWindowFeatures()
+*/
+const WINDOW_HIDEABLE_FEATURES = [
+  "menubar", "toolbar", "locationbar",
+  "personalbar", "statusbar", "scrollbars"
+];
+
+/*
+docShell capabilities to (re)store
+Restored in restoreHistory()
+eg: browser.docShell["allow" + aCapability] = false;
+
+XXX keep these in sync with all the attributes starting
+    with "allow" in /docshell/base/nsIDocShell.idl
+*/
+const CAPABILITIES = [
+  "Subframes", "Plugins", "Javascript", "MetaRedirects", "Images",
+  "DNSPrefetch", "Auth", "WindowControl"
+];
+
+// These are tab events that we listen to.
+const TAB_EVENTS = ["TabOpen", "TabClose", "TabSelect", "TabShow", "TabHide"];
+
+var {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+var {XPCOMUtils} = ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+var {NetUtil} = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
+
+XPCOMUtils.defineLazyServiceGetter(this, "SecMan",
+  "@mozilla.org/scriptsecuritymanager;1", "nsIScriptSecurityManager");
+XPCOMUtils.defineLazyServiceGetter(this, "gScreenManager",
+  "@mozilla.org/gfx/screenmanager;1", "nsIScreenManager");
+XPCOMUtils.defineLazyServiceGetter(this, "uuidGenerator",
+  "@mozilla.org/uuid-generator;1", "nsIUUIDGenerator");
+
+ChromeUtils.defineModuleGetter(this, "AppConstants",
+  "resource://gre/modules/AppConstants.jsm");
+ChromeUtils.defineModuleGetter(this, "Utils",
+  "resource://gre/modules/sessionstore/Utils.jsm");
+ChromeUtils.defineModuleGetter(this, "XPathGenerator",
+  "resource:///modules/sessionstore/XPathGenerator.jsm");
+
+function debug(aMsg) {
+  Services.console.logStringMessage("SessionStore: " + aMsg);
+}
+
+/* :::::::: The Service ::::::::::::::: */
+
+function SessionStoreService() {
+  XPCOMUtils.defineLazyGetter(this, "_prefBranch", function () {
+    return Services.prefs.getBranch("browser.");
+  });
+
+  // minimal interval between two save operations (in milliseconds)
+  XPCOMUtils.defineLazyGetter(this, "_interval", function () {
+    // used often, so caching/observing instead of fetching on-demand
+    this._prefBranch.addObserver("sessionstore.interval", this, true);
+    return this._prefBranch.getIntPref("sessionstore.interval");
+  });
+
+  // when crash recovery is disabled, session data is not written to disk
+  XPCOMUtils.defineLazyGetter(this, "_resume_from_crash", function () {
+    // get crash recovery state from prefs and allow for proper reaction to state changes
+    this._prefBranch.addObserver("sessionstore.resume_from_crash", this, true);
+    return this._prefBranch.getBoolPref("sessionstore.resume_from_crash");
+  });
+}
+
+SessionStoreService.prototype = {
+  classID: Components.ID("{d37ccdf1-496f-4135-9575-037180af010d}"),
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsISessionStore,
+                                         Ci.nsIDOMEventListener,
+                                         Ci.nsIObserver,
+                                         Ci.nsISupportsWeakReference]),
+
+  // xul:tab attributes to (re)store (extensions might want to hook in here);
+  // the favicon is always saved for the about:sessionrestore page
+  xulAttributes: {"image": true},
+
+  // set default load state
+  _loadState: STATE_STOPPED,
+
+  // During the initial restore and setBrowserState calls tracks the number of
+  // windows yet to be restored
+  _restoreCount: -1,
+
+  // whether a setBrowserState call is in progress
+  _browserSetState: false,
+
+  // time in milliseconds (Date.now()) when the session was last written to file
+  _lastSaveTime: 0,
+
+  // time in milliseconds when the session was started (saved across sessions),
+  // defaults to now if no session was restored or timestamp doesn't exist
+  _sessionStartTime: Date.now(),
+
+  // states for all currently opened windows
+  _windows: {},
+
+  // states for all recently closed windows
+  _closedWindows: [],
+
+  // collection of session states yet to be restored
+  _statesToRestore: {},
+
+  // counts the number of crashes since the last clean start
+  _recentCrashes: 0,
+
+  // whether the last window was closed and should be restored
+  _restoreLastWindow: false,
+
+  // tabs to restore in order
+  _tabsToRestore: { visible: [], hidden: [] },
+  _tabsRestoringCount: 0,
+
+  // number of tabs to restore concurrently, pref controlled.
+  _maxConcurrentTabRestores: null,
+
+  // The state from the previous session (after restoring pinned tabs). This
+  // state is persisted and passed through to the next session during an app
+  // restart to make the third party add-on warning not trash the deferred
+  // session
+  _lastSessionState: null,
+
+  // Whether we've been initialized
+  _initialized: false,
+
+  // Mapping from legacy docshellIDs to docshellUUIDs.
+  _docshellUUIDMap: new Map(),
+
+/* ........ Public Getters .............. */
+
+  get canRestoreLastSession() {
+    // Always disallow restoring the previous session when in private browsing
+    return this._lastSessionState;
+  },
+
+  set canRestoreLastSession(val) {
+    // Cheat a bit; only allow false.
+    if (!val)
+      this._lastSessionState = null;
+  },
+
+/* ........ Global Event Handlers .............. */
+
+  /**
+   * Initialize the component
+   */
+  initService: function() {
+    OBSERVING.forEach(function(aTopic) {
+      Services.obs.addObserver(this, aTopic, true);
+    }, this);
+
+    this._max_tabs_undo = this._prefBranch.getIntPref("sessionstore.max_tabs_undo");
+    this._prefBranch.addObserver("sessionstore.max_tabs_undo", this, true);
+
+    this._max_windows_undo = this._prefBranch.getIntPref("sessionstore.max_windows_undo");
+    this._prefBranch.addObserver("sessionstore.max_windows_undo", this, true);
+
+    // this pref is only read at startup, so no need to observe it
+    this._sessionhistory_max_entries =
+      this._prefBranch.getIntPref("sessionhistory.max_entries");
+
+    this._maxConcurrentTabRestores =
+      this._prefBranch.getIntPref("sessionstore.max_concurrent_tabs");
+    this._prefBranch.addObserver("sessionstore.max_concurrent_tabs", this, true);
+
+    // Make sure gRestoreTabsProgressListener has a reference to sessionstore
+    // so that it can make calls back in
+    gRestoreTabsProgressListener.ss = this;
+
+    // get file references
+    this._sessionFile = Services.dirsvc.get("ProfD", Ci.nsIFile);
+    this._sessionFileBackup = this._sessionFile.clone();
+    this._sessionFile.append("sessionstore.json");
+    this._sessionFileBackup.append("sessionstore.bak");
+
+    // get string containing session state
+    var ss = Cc["@mozilla.org/suite/sessionstartup;1"]
+               .getService(Ci.nsISessionStartup);
+    try {
+      if (ss.sessionType != Ci.nsISessionStartup.NO_SESSION)
+        this._initialState = ss.state;
+    }
+    catch(ex) { dump(ex + "\n"); } // no state to restore, which is ok
+
+    if (this._initialState) {
+      try {
+        // If we're doing a DEFERRED session, then we want to pull pinned tabs
+        // out so they can be restored.
+        if (ss.sessionType == Ci.nsISessionStartup.DEFER_SESSION) {
+          let [iniState, remainingState] = this._prepDataForDeferredRestore(this._initialState);
+          // If we have a iniState with windows, that means that we have windows
+          // with app tabs to restore.
+          if (iniState.windows.length)
+            this._initialState = iniState;
+          else
+            this._initialState = null;
+          if (remainingState.windows.length)
+            this._lastSessionState = remainingState;
+        }
+        else {
+          // Get the last deferred session in case the user still wants to
+          // restore it
+          this._lastSessionState = this._initialState.lastSessionState;
+
+          let lastSessionCrashed =
+            this._initialState.session && this._initialState.session.state &&
+            this._initialState.session.state == STATE_RUNNING_STR;
+          if (lastSessionCrashed) {
+            this._recentCrashes = (this._initialState.session &&
+                                   this._initialState.session.recentCrashes || 0) + 1;
+
+            if (this._needsRestorePage(this._initialState, this._recentCrashes)) {
+              // replace the crashed session with a restore-page-only session
+              let pageData = {
+                url: "about:sessionrestore",
+                triggeringPrincipal_base64: Utils.SERIALIZED_SYSTEMPRINCIPAL,
+                formdata: { "#sessionData": JSON.stringify(this._initialState) }
+              };
+              this._initialState = { windows: [{ tabs: [{ entries: [pageData] }] }] };
+            }
+          }
+
+          // Load the session start time from the previous state
+          this._sessionStartTime = this._initialState.session &&
+                                   this._initialState.session.startTime ||
+                                   this._sessionStartTime;
+
+          // make sure that at least the first window doesn't have anything hidden
+          delete this._initialState.windows[0].hidden;
+          // Since nothing is hidden in the first window, it cannot be a popup
+          delete this._initialState.windows[0].isPopup;
+          // clear any lastSessionWindowID attributes since those don't matter
+          // during normal restore
+          this._initialState.windows.forEach(function(aWindow) {
+            delete aWindow.__lastSessionWindowID;
+          });
+        }
+      }
+      catch (ex) { debug("The session file is invalid: " + ex); }
+    }
+
+    if (this._resume_from_crash) {
+      // create a backup if the session data file exists
+      try {
+        if (this._sessionFileBackup.exists())
+          this._sessionFileBackup.remove(false);
+        if (this._sessionFile.exists())
+          this._sessionFile.copyTo(null, this._sessionFileBackup.leafName);
+      }
+      catch (ex) { Cu.reportError(ex); } // file was write-locked?
+    }
+
+    // at this point, we've as good as resumed the session, so we can
+    // clear the resume_session_once flag, if it's set
+    if (this._loadState != STATE_QUITTING &&
+        this._prefBranch.getBoolPref("sessionstore.resume_session_once"))
+      this._prefBranch.setBoolPref("sessionstore.resume_session_once", false);
+
+    this._initialized = true;
+  },
+
+  /**
+   * Start tracking a window.
+   * This function also initializes the component if it's not already
+   * initialized.
+   */
+  init: function sss_init(aWindow) {
+    // Initialize the service if needed.
+    if (!this._initialized)
+      this.initService();
+
+    if (aWindow) {
+      this.onLoad(aWindow);
+    } else if (this._loadState == STATE_STOPPED) {
+      // If init is being called with a null window, it's possible that we
+      // just want to tell sessionstore that a session is live (as is the case
+      // with starting Firefox with -private, for example; see bug 568816),
+      // so we should mark the load state as running to make sure that
+      // things like setBrowserState calls will succeed in restoring the session.
+      this._loadState = STATE_RUNNING;
+    }
+  },
+  /**
+   * Called on application shutdown, after notifications:
+   * quit-application-granted, quit-application
+   */
+  _uninit: function sss_uninit() {
+    // save all data for session resuming
+    this.saveState(true);
+
+    // clear out _tabsToRestore in case it's still holding refs
+    this._tabsToRestore.visible = null;
+    this._tabsToRestore.hidden = null;
+
+    // remove the ref to us from the progress listener
+    gRestoreTabsProgressListener.ss = null;
+
+    // Make sure to break our cycle with the save timer
+    if (this._saveTimer) {
+      this._saveTimer.cancel();
+      this._saveTimer = null;
+    }
+  },
+
+  /**
+   * Handle notifications
+   */
+  observe: function sss_observe(aSubject, aTopic, aData) {
+    switch (aTopic) {
+    case "domwindowclosed": // catch closed windows
+      this.onClose(aSubject);
+      break;
+    case "quit-application-requested":
+      // get a current snapshot of all windows
+      this._forEachBrowserWindow(function(aWindow) {
+        this._collectWindowData(aWindow);
+      });
+      DirtyWindows.clear();
+      break;
+    case "quit-application-granted":
+      // freeze the data at what we've got (ignoring closing windows)
+      this._loadState = STATE_QUITTING;
+      break;
+    case "browser-lastwindow-close-granted":
+      // last browser window is quitting.
+      // remember to restore the last window when another browser window is openend
+      // do not account for pref(resume_session_once) at this point, as it might be
+      // set by another observer getting this notice after us
+      this._restoreLastWindow = true;
+      break;
+    case "quit-application":
+      if (aData == "restart" && !this._isSwitchingProfile()) {
+        this._prefBranch.setBoolPref("sessionstore.resume_session_once", true);
+        // The browser:purge-session-history notification fires after the
+        // quit-application notification so unregister the
+        // browser:purge-session-history notification to prevent clearing
+        // session data on disk on a restart.  It is also unnecessary to
+        // perform any other sanitization processing on a restart as the
+        // browser is about to exit anyway.
+        Services.obs.removeObserver(this, "browser:purge-session-history");
+      }
+
+      if (aData != "restart") {
+        // Throw away the previous session on shutdown
+        this._lastSessionState = null;
+      }
+
+      this._loadState = STATE_QUITTING; // just to be sure
+      this._uninit();
+      break;
+    case "browser:purge-session-history": // catch sanitization
+      this._clearDisk();
+      // If the browser is shutting down, simply return after clearing the
+      // session data on disk as this notification fires after the
+      // quit-application notification so the browser is about to exit.
+      if (this._loadState == STATE_QUITTING)
+        return;
+      this._lastSessionState = null;
+      let openWindows = {};
+      this._forEachBrowserWindow(function(aWindow) {
+        //Hide "Restore Last Session" menu item
+        let restoreItem = aWindow.document.getElementById("historyRestoreLastSession");
+        restoreItem.setAttribute("disabled", "true");
+
+        Array.from(aWindow.getBrowser().tabs).forEach(function(aTab) {
+          delete aTab.linkedBrowser.__SS_data;
+          delete aTab.linkedBrowser.__SS_formDataSaved;
+          if (aTab.linkedBrowser.__SS_restoreState)
+            this._resetTabRestoringState(aTab);
+        });
+        openWindows[aWindow.__SSi] = true;
+      });
+      // also clear all data about closed tabs and windows
+      for (let ix in this._windows) {
+        if (ix in openWindows) {
+          this._windows[ix]._closedTabs = [];
+        }
+        else {
+          delete this._windows[ix];
+        }
+      }
+      // also clear all data about closed windows
+      this._closedWindows = [];
+      // give the tabbrowsers a chance to clear their histories first
+      if (this._getMostRecentBrowserWindow())
+        Services.tm.mainThread.dispatch(this.saveState.bind(this, true),
+          Ci.nsIThread.DISPATCH_NORMAL);
+      else if (this._loadState == STATE_RUNNING)
+        this.saveState(true);
+      break;
+    case "nsPref:changed": // catch pref changes
+      switch (aData) {
+      // if the user decreases the max number of closed tabs they want
+      // preserved update our internal states to match that max
+      case "sessionstore.max_tabs_undo":
+        this._max_tabs_undo = this._prefBranch.getIntPref("sessionstore.max_tabs_undo");
+        for (let ix in this._windows) {
+          this._windows[ix]._closedTabs.splice(this._max_tabs_undo, this._windows[ix]._closedTabs.length);
+        }
+        break;
+      case "sessionstore.max_windows_undo":
+        this._max_windows_undo = this._prefBranch.getIntPref("sessionstore.max_windows_undo");
+        this._capClosedWindows();
+        break;
+      case "sessionstore.interval":
+        this._interval = this._prefBranch.getIntPref("sessionstore.interval");
+        // reset timer and save
+        if (this._saveTimer) {
+          this._saveTimer.cancel();
+          this._saveTimer = null;
+        }
+        this.saveStateDelayed(null, -1);
+        break;
+      case "sessionstore.resume_from_crash":
+        this._resume_from_crash = this._prefBranch.getBoolPref("sessionstore.resume_from_crash");
+        // either create the file with crash recovery information or remove it
+        // (when _loadState is not STATE_RUNNING, that file is used for session resuming instead)
+        if (this._resume_from_crash)
+          this.saveState(true);
+        else if (this._loadState == STATE_RUNNING)
+          this._clearDisk();
+        break;
+      case "sessionstore.max_concurrent_tabs":
+        this._maxConcurrentTabRestores =
+          this._prefBranch.getIntPref("sessionstore.max_concurrent_tabs");
+        break;
+      }
+      break;
+    case "timer-callback": // timer call back for delayed saving
+      this._saveTimer = null;
+      this.saveState();
+      break;
+    }
+  },
+
+/* ........ Window Event Handlers .............. */
+
+  /**
+   * Implement nsIDOMEventListener for handling various window and tab events
+   */
+  handleEvent: function sss_handleEvent(aEvent) {
+    var win = aEvent.currentTarget.ownerDocument.defaultView;
+    switch (aEvent.type) {
+      case "load":
+        // If __SS_restore_data is set, then we need to restore the document
+        // (form data, scrolling, etc.). This will only happen when a tab is
+        // first restored.
+        if (aEvent.currentTarget.__SS_restore_data)
+          this.restoreDocument(win, aEvent.currentTarget, aEvent);
+        // We still need to call onTabLoad, so fall through to "pageshow" case.
+      case "pageshow":
+        this.onTabLoad(win, aEvent.currentTarget, aEvent);
+        break;
+      case "input":
+      case "DOMAutoComplete":
+        this.onTabInput(win, aEvent.currentTarget);
+        break;
+      case "TabOpen":
+        this.onTabAdd(win, aEvent.originalTarget);
+        break;
+      case "TabClose":
+        // aEvent.detail determines if the tab was closed by moving to a different window
+        if (!aEvent.detail)
+          this.onTabClose(win, aEvent.originalTarget);
+        this.onTabRemove(win, aEvent.originalTarget);
+        break;
+      case "TabSelect":
+        this.onTabSelect(win);
+        break;
+      case "TabShow":
+        this.onTabShow(aEvent.originalTarget);
+        break;
+      case "TabHide":
+        this.onTabHide(aEvent.originalTarget);
+        break;
+    }
+  },
+
+  /**
+   * If it's the first window load since app start...
+   * - determine if we're reloading after a crash or a forced-restart
+   * - restore window state
+   * - restart downloads
+   * Set up event listeners for this window's tabs
+   * @param aWindow
+   *        Window reference
+   */
+  onLoad: function sss_onLoad(aWindow) {
+    // return if window has already been initialized
+    if (aWindow && aWindow.__SSi && this._windows[aWindow.__SSi])
+      return;
+
+    // ignore non-browser windows and windows opened while shutting down
+    if (aWindow.document.documentElement.getAttribute("windowtype") != "navigator:browser" ||
+        this._loadState == STATE_QUITTING)
+      return;
+
+    // assign it a unique identifier (timestamp)
+    aWindow.__SSi = "window" + Date.now();
+
+    // and create its data object
+    this._windows[aWindow.__SSi] = { tabs: [], selected: 0, _closedTabs: [] };
+
+    if (!this._isWindowLoaded(aWindow))
+      this._windows[aWindow.__SSi]._restoring = true;
+    if (!aWindow.toolbar.visible)
+      this._windows[aWindow.__SSi].isPopup = true;
+
+    // perform additional initialization when the first window is loading
+    if (this._loadState == STATE_STOPPED) {
+      this._loadState = STATE_RUNNING;
+      this._lastSaveTime = Date.now();
+
+      // restore a crashed session resp. resume the last session if requested
+      if (this._initialState) {
+        // make sure that the restored tabs are first in the window
+        this._initialState._firstTabs = true;
+        this._restoreCount = this._initialState.windows ? this._initialState.windows.length : 0;
+        this.restoreWindow(aWindow, this._initialState,
+                           this._isCmdLineEmpty(aWindow));
+        delete this._initialState;
+
+        // _loadState changed from "stopped" to "running"
+        // force a save operation so that crashes happening during startup are correctly counted
+        this.saveState(true);
+      }
+      else {
+        // Nothing to restore, notify observers things are complete.
+        this.windowToFocus = aWindow;
+        Services.tm.mainThread.dispatch(this, Ci.nsIThread.DISPATCH_NORMAL);
+
+        // the next delayed save request should execute immediately
+        this._lastSaveTime -= this._interval;
+      }
+    }
+    // this window was opened by _openWindowWithState
+    else if (!this._isWindowLoaded(aWindow)) {
+      let followUp = this._statesToRestore[aWindow.__SS_restoreID].windows.length == 1;
+      this.restoreWindow(aWindow, this._statesToRestore[aWindow.__SS_restoreID], true, followUp);
+    }
+    else if (this._restoreLastWindow && aWindow.toolbar.visible &&
+             this._closedWindows.length) {
+      // default to the most-recently closed window
+      // don't use popup windows
+      let closedWindowState = null;
+      let closedWindowIndex;
+      for (let i = 0; i < this._closedWindows.length; i++) {
+        // Take the first non-popup, point our object at it, and break out.
+        if (!this._closedWindows[i].isPopup) {
+          closedWindowState = this._closedWindows[i];
+          closedWindowIndex = i;
+          break;
+        }
+      }
+
+      if (closedWindowState) {
+        let newWindowState;
+        if (AppConstants.platform == "macosx" || !this._doResumeSession()) {
+          // We want to split the window up into pinned tabs and unpinned tabs.
+          // Pinned tabs should be restored. If there are any remaining tabs,
+          // they should be added back to _closedWindows.
+          // We'll cheat a little bit and reuse _prepDataForDeferredRestore
+          // even though it wasn't built exactly for this.
+          let [appTabsState, normalTabsState] =
+            this._prepDataForDeferredRestore({ windows: [closedWindowState] });
+
+          // These are our pinned tabs, which we should restore
+          if (appTabsState.windows.length) {
+            newWindowState = appTabsState.windows[0];
+            delete newWindowState.__lastSessionWindowID;
+          }
+
+          // In case there were no unpinned tabs, remove the window from _closedWindows
+          if (!normalTabsState.windows.length) {
+            this._closedWindows.splice(closedWindowIndex, 1);
+          }
+          // Or update _closedWindows with the modified state
+          else {
+            delete normalTabsState.windows[0].__lastSessionWindowID;
+            this._closedWindows[closedWindowIndex] = normalTabsState.windows[0];
+          }
+        }
+        else {
+          // If we're just restoring the window, make sure it gets removed from
+          // _closedWindows.
+          this._closedWindows.splice(closedWindowIndex, 1);
+          newWindowState = closedWindowState;
+          delete newWindowState.hidden;
+        }
+
+        if (newWindowState) {
+          // Ensure that the window state isn't hidden
+          this._restoreCount = 1;
+          let state = { windows: [newWindowState] };
+          this.restoreWindow(aWindow, state, this._isCmdLineEmpty(aWindow));
+        }
+      }
+      // we actually restored the session just now.
+      this._prefBranch.setBoolPref("sessionstore.resume_session_once", false);
+    }
+    if (this._restoreLastWindow && aWindow.toolbar.visible) {
+      // always reset (if not a popup window)
+      // we don't want to restore a window directly after, for example,
+      // undoCloseWindow was executed.
+      this._restoreLastWindow = false;
+    }
+
+    var tabbrowser = aWindow.getBrowser();
+
+    // add tab change listeners to all already existing tabs
+    for (let i = 0; i < tabbrowser.tabs.length; i++) {
+      this.onTabAdd(aWindow, tabbrowser.tabs[i], true);
+    }
+    // notification of tab add/remove/selection/show/hide
+    TAB_EVENTS.forEach(function(aEvent) {
+      tabbrowser.tabContainer.addEventListener(aEvent, this, true);
+    }, this);
+  },
+
+  /**
+   * On window close...
+   * - remove event listeners from tabs
+   * - save all window data
+   * @param aWindow
+   *        Window reference
+   */
+  onClose: function sss_onClose(aWindow) {
+    // this window was about to be restored - conserve its original data, if any
+    let isFullyLoaded = this._isWindowLoaded(aWindow);
+    if (!isFullyLoaded) {
+      if (!aWindow.__SSi)
+        aWindow.__SSi = "window" + Date.now();
+      this._windows[aWindow.__SSi] = this._statesToRestore[aWindow.__SS_restoreID];
+      delete this._statesToRestore[aWindow.__SS_restoreID];
+      delete aWindow.__SS_restoreID;
+    }
+
+    // ignore windows not tracked by SessionStore
+    if (!aWindow.__SSi || !this._windows[aWindow.__SSi]) {
+      return;
+    }
+
+    if (this.windowToFocus && this.windowToFocus == aWindow) {
+      delete this.windowToFocus;
+    }
+
+    var tabbrowser = aWindow.getBrowser();
+
+    TAB_EVENTS.forEach(function(aEvent) {
+      tabbrowser.tabContainer.removeEventListener(aEvent, this, true);
+    }, this);
+
+    // remove the progress listener for this window
+    try {
+     tabbrowser.removeTabsProgressListener(gRestoreTabsProgressListener);
+    } catch (ex) {};
+
+    let winData = this._windows[aWindow.__SSi];
+    if (this._loadState == STATE_RUNNING) { // window not closed during a regular shut-down
+      // update all window data for a last time
+      this._collectWindowData(aWindow);
+
+      if (isFullyLoaded) {
+        winData.title = aWindow.content.document.title || tabbrowser.selectedTab.label;
+        winData.title = this._replaceLoadingTitle(winData.title, tabbrowser,
+                                                  tabbrowser.selectedTab);
+        this._updateCookies([winData]);
+      }
+
+      // save the window if it has multiple tabs or a single saveable tab
+      if (winData.tabs.length > 1 ||
+          (winData.tabs.length == 1 && this._shouldSaveTabState(winData.tabs[0]))) {
+        this._closedWindows.unshift(winData);
+        this._capClosedWindows();
+      }
+
+      // clear this window from the list
+      delete this._windows[aWindow.__SSi];
+
+      // save the state without this window to disk
+      this.saveStateDelayed();
+    }
+
+    for (let i = 0; i < tabbrowser.tabs.length; i++) {
+      this.onTabRemove(aWindow, tabbrowser.tabs[i], true);
+    }
+
+    // Cache the window state until it is completely gone.
+    DyingWindowCache.set(aWindow, winData);
+
+    delete aWindow.__SSi;
+  },
+
+  /**
+   * set up listeners for a new tab
+   * @param aWindow
+   *        Window reference
+   * @param aTab
+   *        Tab reference
+   * @param aNoNotification
+   *        bool Do not save state if we're updating an existing tab
+   */
+  onTabAdd: function sss_onTabAdd(aWindow, aTab, aNoNotification) {
+    let browser = aTab.linkedBrowser;
+    browser.addEventListener("load", this, true);
+    browser.addEventListener("pageshow", this, true);
+    browser.addEventListener("input", this, true);
+    browser.addEventListener("DOMAutoComplete", this, true);
+
+    if (!aNoNotification) {
+      this.saveStateDelayed(aWindow);
+    }
+
+    this._updateCrashReportURL(aWindow);
+  },
+
+  /**
+   * remove listeners for a tab
+   * @param aWindow
+   *        Window reference
+   * @param aTab
+   *        Tab reference
+   * @param aNoNotification
+   *        bool Do not save state if we're updating an existing tab
+   */
+  onTabRemove: function sss_onTabRemove(aWindow, aTab, aNoNotification) {
+    let browser = aTab.linkedBrowser;
+    browser.removeEventListener("load", this, true);
+    browser.removeEventListener("pageshow", this, true);
+    browser.removeEventListener("change", this, true);
+    browser.removeEventListener("input", this, true);
+    browser.removeEventListener("DOMAutoComplete", this, true);
+
+    delete browser.__SS_data;
+
+    // If this tab was in the middle of restoring or still needs to be restored,
+    // we need to reset that state. If the tab was restoring, we will attempt to
+    // restore the next tab.
+    let previousState = browser.__SS_restoreState;
+    if (previousState) {
+      this._resetTabRestoringState(aTab);
+      if (previousState == TAB_STATE_RESTORING)
+        this.restoreNextTab();
+    }
+
+    if (!aNoNotification) {
+      this.saveStateDelayed(aWindow);
+    }
+  },
+
+  /**
+   * When a tab closes, collect its properties
+   * @param aWindow
+   *        Window reference
+   * @param aTab
+   *        Tab reference
+   */
+  onTabClose: function sss_onTabClose(aWindow, aTab) {
+    // notify the tabbrowser that the tab state will be retrieved for the last time
+    // (so that extension authors can easily set data on soon-to-be-closed tabs)
+    var event = aWindow.document.createEvent("Events");
+    event.initEvent("SSTabClosing", true, false);
+    aTab.dispatchEvent(event);
+
+    // don't update our internal state if we don't have to
+    if (this._max_tabs_undo == 0) {
+      return;
+    }
+
+    // make sure that the tab related data is up-to-date
+    var tabState = this._collectTabData(aTab);
+    this._updateTextAndScrollDataForTab(aWindow, aTab.linkedBrowser, tabState);
+
+    // store closed-tab data for undo
+    if (this._shouldSaveTabState(tabState)) {
+      aTab.tabData = { state: tabState };
+      var closedTabs = this._windows[aWindow.__SSi]._closedTabs;
+      closedTabs.unshift(aTab.tabData);
+      if (closedTabs.length > this._max_tabs_undo)
+        closedTabs.length = this._max_tabs_undo;
+    };
+  },
+
+  /**
+   * When a tab loads, save state.
+   * @param aWindow
+   *        Window reference
+   * @param aBrowser
+   *        Browser reference
+   * @param aEvent
+   *        Event obj
+   */
+  onTabLoad: function sss_onTabLoad(aWindow, aBrowser, aEvent) {
+    // react on "load" and solitary "pageshow" events (the first "pageshow"
+    // following "load" is too late for deleting the data caches)
+    // It's possible to get a load event after calling stop on a browser (when
+    // overwriting tabs). We want to return early if the tab hasn't been restored yet.
+    if ((aEvent.type != "load" && !aEvent.persisted) ||
+        (aBrowser.__SS_restoreState &&
+         aBrowser.__SS_restoreState == TAB_STATE_NEEDS_RESTORE)) {
+      return;
+    }
+
+    delete aBrowser.__SS_data;
+    this.saveStateDelayed(aWindow);
+
+    // attempt to update the current URL we send in a crash report
+    this._updateCrashReportURL(aWindow);
+  },
+
+  /**
+   * Called when a browser sends the "input" notification
+   * @param aWindow
+   *        Window reference
+   * @param aBrowser
+   *        Browser reference
+   */
+  onTabInput: function sss_onTabInput(aWindow, aBrowser) {
+    this.saveStateDelayed(aWindow, 3000);
+  },
+
+  /**
+   * When a tab is selected, save session data
+   * @param aWindow
+   *        Window reference
+   */
+  onTabSelect: function sss_onTabSelect(aWindow) {
+    if (this._loadState == STATE_RUNNING) {
+      this._windows[aWindow.__SSi].selected = aWindow.getBrowser().tabContainer.selectedIndex;
+
+      let tab = aWindow.getBrowser().selectedTab;
+      // If __SS_restoreState is still on the browser and it is
+      // TAB_STATE_NEEDS_RESTORE, then then we haven't restored
+      // this tab yet. Explicitly call restoreTab to kick off the restore.
+      if (tab.linkedBrowser.__SS_restoreState &&
+          tab.linkedBrowser.__SS_restoreState == TAB_STATE_NEEDS_RESTORE)
+        this.restoreTab(tab);
+
+      // attempt to update the current URL we send in a crash report
+      this._updateCrashReportURL(aWindow);
+    }
+  },
+
+  onTabShow: function sss_onTabShow(aTab) {
+    // If the tab hasn't been restored yet, move it into the right _tabsToRestore bucket
+    if (aTab.linkedBrowser.__SS_restoreState &&
+        aTab.linkedBrowser.__SS_restoreState == TAB_STATE_NEEDS_RESTORE) {
+      this._tabsToRestore.hidden.splice(this._tabsToRestore.hidden.indexOf(aTab), 1);
+      // Just put it at the end of the list of visible tabs;
+      this._tabsToRestore.visible.push(aTab);
+    }
+  },
+
+  onTabHide: function sss_onTabHide(aTab) {
+    // If the tab hasn't been restored yet, move it into the right _tabsToRestore bucket
+    if (aTab.linkedBrowser.__SS_restoreState &&
+        aTab.linkedBrowser.__SS_restoreState == TAB_STATE_NEEDS_RESTORE) {
+      this._tabsToRestore.visible.splice(this._tabsToRestore.visible.indexOf(aTab), 1);
+      // Just put it at the end of the list of hidden tabs;
+      this._tabsToRestore.hidden.push(aTab);
+    }
+  },
+
+/* ........ nsISessionStore API .............. */
+
+  getBrowserState: function sss_getBrowserState() {
+    return this._toJSONString(this._getCurrentState());
+  },
+
+  setBrowserState: function sss_setBrowserState(aState) {
+    this._handleClosedWindows();
+
+    try {
+      var state = JSON.parse(aState);
+    }
+    catch (ex) { /* invalid state object - don't restore anything */ }
+    if (!state || !state.windows)
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+
+    this._browserSetState = true;
+
+    // Make sure _tabsToRestore is emptied out
+    this._resetRestoringState();
+
+    var window = this._getMostRecentBrowserWindow();
+    if (!window) {
+      this._restoreCount = 1;
+      this._openWindowWithState(state);
+      return;
+    }
+
+    // close all other browser windows
+    this._forEachBrowserWindow(function(aWindow) {
+      if (aWindow != window) {
+        aWindow.close();
+        this.onClose(aWindow);
+      }
+    });
+
+    // make sure closed window data isn't kept
+    this._closedWindows = [];
+
+    // determine how many windows are meant to be restored
+    this._restoreCount = state.windows ? state.windows.length : 0;
+
+    // restore to the given state
+    this.restoreWindow(window, state, true);
+  },
+
+  getWindowState: function sss_getWindowState(aWindow) {
+    if ("__SSi" in aWindow) {
+      return this._toJSONString(this._getWindowState(aWindow));
+    }
+
+    if (DyingWindowCache.has(aWindow)) {
+      let data = DyingWindowCache.get(aWindow);
+      return this._toJSONString({ windows: [data] });
+    }
+
+    throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+  },
+
+  setWindowState: function sss_setWindowState(aWindow, aState, aOverwrite) {
+    if (!aWindow.__SSi)
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+
+    this.restoreWindow(aWindow, aState, aOverwrite);
+  },
+
+  getTabState: function sss_getTabState(aTab) {
+    if (!aTab.ownerDocument || !aTab.ownerDocument.defaultView.__SSi)
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+
+    var tabState = this._collectTabData(aTab);
+
+    var window = aTab.ownerDocument.defaultView;
+    this._updateTextAndScrollDataForTab(window, aTab.linkedBrowser, tabState);
+
+    return this._toJSONString(tabState);
+  },
+
+  setTabState: function sss_setTabState(aTab, aState) {
+    var tabState = JSON.parse(aState);
+    if (!tabState.entries || !aTab.ownerDocument || !aTab.ownerDocument.defaultView.__SSi)
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+
+    var window = aTab.ownerDocument.defaultView;
+    this._sendWindowStateEvent(window, "Busy");
+    this.restoreHistoryPrecursor(window, [aTab], [tabState], 0, 0, 0);
+  },
+
+  duplicateTab: function sss_duplicateTab(aWindow, aTab, aDelta, aRelated) {
+    if (!aTab.ownerDocument || !aTab.ownerDocument.defaultView.__SSi ||
+        aWindow && !aWindow.getBrowser)
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+
+    var tabState = this._collectTabData(aTab, true);
+    var sourceWindow = aTab.ownerDocument.defaultView;
+    this._updateTextAndScrollDataForTab(sourceWindow, aTab.linkedBrowser, tabState, true);
+    tabState.index += aDelta;
+    tabState.index = Math.max(1, Math.min(tabState.index, tabState.entries.length));
+
+    if (aWindow) {
+      this._sendWindowStateEvent(aWindow, "Busy");
+      var newTab = aWindow.getBrowser()
+                          .addTab(null, { relatedToCurrent: aRelated });
+      this.restoreHistoryPrecursor(aWindow, [newTab], [tabState], 0, 0, 0);
+      return newTab;
+    }
+
+    var state = { windows: [{ tabs: [tabState] }] };
+    this.windowToFocus = this._openWindowWithState(state);
+    return null;
+  },
+
+  _getClosedTabs: function sss_getClosedTabs(aWindow) {
+    if (!aWindow.__SSi)
+      return this._toJSONString(aWindow.__SS_dyingCache._closedTabs);
+
+    var closedTabs = this._windows[aWindow.__SSi]._closedTabs;
+    closedTabs = closedTabs.concat(aWindow.getBrowser().savedBrowsers);
+    closedTabs = closedTabs.filter(function(aTabData, aIndex, aArray) {
+      return aArray.indexOf(aTabData) == aIndex;
+    });
+    return closedTabs;
+  },
+
+  getClosedTabCount: function sss_getClosedTabCount(aWindow) {
+    if ("__SSi" in aWindow) {
+      return this._windows[aWindow.__SSi]._closedTabs.length;
+    }
+
+    if (DyingWindowCache.has(aWindow)) {
+      return DyingWindowCache.get(aWindow)._closedTabs.length;
+    }
+
+    throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+  },
+
+  getClosedTabData: function sss_getClosedTabData(aWindow) {
+    if ("__SSi" in aWindow) {
+      return this._toJSONString(this._windows[aWindow.__SSi]._closedTabs);
+    }
+
+    if (DyingWindowCache.has(aWindow)) {
+      let data = DyingWindowCache.get(aWindow);
+      return this._toJSONString(data._closedTabs);
+    }
+
+    throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+  },
+
+  undoCloseTab: function sss_undoCloseTab(aWindow, aIndex) {
+    if (!aWindow.__SSi)
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+
+    var closedTabs = this._getClosedTabs(aWindow);
+    if (!(aIndex in closedTabs))
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+
+    // fetch the data of closed tab, while removing it from the array
+    let closedTab = closedTabs[aIndex];
+    if (aIndex in this._windows[aWindow.__SSi]._closedTabs)
+      this._windows[aWindow.__SSi]._closedTabs.splice(aIndex, 1);
+    var tabbrowser = aWindow.getBrowser();
+    var index = tabbrowser.savedBrowsers.indexOf(closedTab);
+    this._sendWindowStateEvent(aWindow, "Busy");
+    if (index != -1)
+      // SeaMonkey has its own undoclosetab functionality
+      return tabbrowser.restoreTab(index);
+
+    // create a new tab
+    var tab = tabbrowser.addTab();
+
+    // restore the tab's position
+    tabbrowser.moveTabTo(tab, closedTab.pos);
+
+    // restore tab content
+    this.restoreHistoryPrecursor(aWindow, [tab], [closedTab.state], 1, 0, 0);
+
+    // focus the tab's content area (bug 342432)
+    tab.linkedBrowser.focus();
+
+    return tab;
+  },
+
+  forgetClosedTab: function sss_forgetClosedTab(aWindow, aIndex) {
+    if (!aWindow.__SSi)
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+
+    var closedTabs = this._getClosedTabs(aWindow);
+    if (!(aIndex in closedTabs))
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+
+    // remove closed tab from the array
+    var closedTab = closedTabs[aIndex];
+    if (aIndex in this._windows[aWindow.__SSi]._closedTabs)
+      this._windows[aWindow.__SSi]._closedTabs.splice(aIndex, 1);
+    var tabbrowser = aWindow.getBrowser();
+    var index = tabbrowser.savedBrowsers.indexOf(closedTab);
+    if (index != -1)
+      tabbrowser.forgetSavedBrowser(aIndex);
+  },
+
+  getClosedWindowCount: function sss_getClosedWindowCount() {
+    return this._closedWindows.length;
+  },
+
+  getClosedWindowData: function sss_getClosedWindowData() {
+    return this._toJSONString(this._closedWindows);
+  },
+
+  undoCloseWindow: function sss_undoCloseWindow(aIndex) {
+    if (!(aIndex in this._closedWindows))
+      return null;
+
+    // reopen the window
+    let state = { windows: this._closedWindows.splice(aIndex, 1) };
+    let window = this._openWindowWithState(state);
+    this.windowToFocus = window;
+    return window;
+  },
+
+  forgetClosedWindow: function sss_forgetClosedWindow(aIndex) {
+    // default to the most-recently closed window
+    aIndex = aIndex || 0;
+    if (!(aIndex in this._closedWindows))
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+
+    // remove closed window from the array
+    this._closedWindows.splice(aIndex, 1);
+  },
+
+  getWindowValue: function sss_getWindowValue(aWindow, aKey) {
+    if ("__SSi" in aWindow) {
+      var data = this._windows[aWindow.__SSi].extData || {};
+      return data[aKey] || "";
+    }
+    if (DyingWindowCache.has(aWindow)) {
+      let data = DyingWindowCache.get(aWindow).extData || {};
+      return data[aKey] || "";
+    }
+    throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+  },
+
+  setWindowValue: function sss_setWindowValue(aWindow, aKey, aStringValue) {
+    if (aWindow.__SSi) {
+      if (!this._windows[aWindow.__SSi].extData) {
+        this._windows[aWindow.__SSi].extData = {};
+      }
+      this._windows[aWindow.__SSi].extData[aKey] = aStringValue;
+      this.saveStateDelayed(aWindow);
+    }
+    else {
+      throw (Components.returnCode = Cr.NS_ERROR_INVALID_ARG);
+    }
+  },
+
+  deleteWindowValue: function sss_deleteWindowValue(aWindow, aKey) {
+    if (aWindow.__SSi && this._windows[aWindow.__SSi].extData &&
+        this._windows[aWindow.__SSi].extData[aKey])
+      delete this._windows[aWindow.__SSi].extData[aKey];
+  },
+
+  getTabValue: function sss_getTabValue(aTab, aKey) {
+    let data = {};
+    if (aTab.__SS_extdata) {
+      data = aTab.__SS_extdata;
+    }
+    else if (aTab.linkedBrowser.__SS_data && aTab.linkedBrowser.__SS_data.extData) {
+      // If the tab hasn't been fully restored, get the data from the to-be-restored data
+      data = aTab.linkedBrowser.__SS_data.extData;
+    }
+    return data[aKey] || "";
+  },
+
+  setTabValue: function sss_setTabValue(aTab, aKey, aStringValue) {
+    // If the tab hasn't been restored, then set the data there, otherwise we
+    // could lose newly added data.
+    let saveTo;
+    if (aTab.__SS_extdata) {
+      saveTo = aTab.__SS_extdata;
+    }
+    else if (aTab.linkedBrowser.__SS_data && aTab.linkedBrowser.__SS_data.extData) {
+      saveTo = aTab.linkedBrowser.__SS_data.extData;
+    }
+    else {
+      aTab.__SS_extdata = {};
+      saveTo = aTab.__SS_extdata;
+    }
+    saveTo[aKey] = aStringValue;
+    this.saveStateDelayed(aTab.ownerDocument.defaultView);
+  },
+
+  deleteTabValue: function sss_deleteTabValue(aTab, aKey) {
+    // We want to make sure that if data is accessed early, we attempt to delete
+    // that data from __SS_data as well. Otherwise we'll throw in cases where
+    // data can be set or read.
+    let deleteFrom = null;
+    if (aTab.__SS_extdata) {
+      deleteFrom = aTab.__SS_extdata;
+    }
+    else if (aTab.linkedBrowser.__SS_data && aTab.linkedBrowser.__SS_data.extData) {
+      deleteFrom = aTab.linkedBrowser.__SS_data.extData;
+    }
+
+    if (deleteFrom && deleteFrom[aKey])
+      delete deleteFrom[aKey];
+  },
+
+  persistTabAttribute: function sss_persistTabAttribute(aName) {
+    if (aName in this.xulAttributes)
+      return; // this attribute is already being tracked
+
+    this.xulAttributes[aName] = true;
+    this.saveStateDelayed();
+  },
+
+  doRestoreLastWindow: function sss_doRestoreLastWindow() {
+    let state = null;
+    this._closedWindows.forEach(function(aWinState) {
+      if (!state && !aWinState.isPopup) {
+        state = aWinState;
+      }
+    });
+    return (this._restoreLastWindow && state &&
+            this._doResumeSession());
+  },
+
+  /**
+   * Restores the session state stored in _lastSessionState. This will attempt
+   * to merge data into the current session. If a window was opened at startup
+   * with pinned tab(s), then the remaining data from the previous session for
+   * that window will be opened into that winddow. Otherwise new windows will
+   * be opened.
+   */
+  restoreLastSession: function sss_restoreLastSession() {
+    // Use the public getter since it also checks PB mode
+    if (!this.canRestoreLastSession)
+      throw (Components.returnCode = Cr.NS_ERROR_FAILURE);
+
+    // First collect each window with its id...
+    let windows = {};
+    this._forEachBrowserWindow(function(aWindow) {
+      if (aWindow.__SS_lastSessionWindowID)
+        windows[aWindow.__SS_lastSessionWindowID] = aWindow;
+    });
+
+    let lastSessionState = this._lastSessionState;
+
+    // This shouldn't ever be the case...
+    if (!lastSessionState.windows.length)
+      throw (Components.returnCode = Cr.NS_ERROR_UNEXPECTED);
+
+    // We're technically doing a restore, so set things up so we send the
+    // notification when we're done. We want to send "sessionstore-browser-state-restored".
+    this._restoreCount = lastSessionState.windows.length;
+    this._browserSetState = true;
+
+    // We want to re-use the last opened window instead of opening a new one in
+    // the case where it's "empty" and not associated with a window in the session.
+    // We will do more processing via _prepWindowToRestoreInto if we need to use
+    // the lastWindow.
+    let lastWindow = this._getMostRecentBrowserWindow();
+    let canUseLastWindow = lastWindow &&
+                           !lastWindow.__SS_lastSessionWindowID;
+
+    // Restore into windows or open new ones as needed.
+    for (let i = 0; i < lastSessionState.windows.length; i++) {
+      let winState = lastSessionState.windows[i];
+      let lastSessionWindowID = winState.__lastSessionWindowID;
+      // delete lastSessionWindowID so we don't add that to the window again
+      delete winState.__lastSessionWindowID;
+
+      // See if we can use an open window. First try one that is associated with
+      // the state we're trying to restore and then fallback to the last selected
+      // window.
+      let windowToUse = windows[lastSessionWindowID];
+      if (!windowToUse && canUseLastWindow) {
+        windowToUse = lastWindow;
+        canUseLastWindow = false;
+      }
+
+      let [canUseWindow, canOverwriteTabs] = this._prepWindowToRestoreInto(windowToUse);
+
+      // If there's a window already open that we can restore into, use that
+      if (canUseWindow) {
+        // Since we're not overwriting existing tabs, we want to merge _closedTabs,
+        // putting existing ones first. Then make sure we're respecting the max pref.
+        if (winState._closedTabs && winState._closedTabs.length) {
+          let curWinState = this._windows[windowToUse.__SSi];
+          curWinState._closedTabs = curWinState._closedTabs.concat(winState._closedTabs);
+          curWinState._closedTabs.splice(this._max_tabs_undo, curWinState._closedTabs.length);
+        }
+
+        // Restore into that window - pretend it's a followup since we'll already
+        // have a focused window.
+        //XXXzpao This is going to merge extData together (taking what was in
+        //        winState over what is in the window already. The hack we have
+        //        in _preWindowToRestoreInto will prevent most (all?) Panorama
+        //        weirdness but we will still merge other extData.
+        //        Bug 588217 should make this go away by merging the group data.
+        this.restoreWindow(windowToUse, { windows: [winState] }, canOverwriteTabs, true);
+      }
+      else {
+        this._openWindowWithState({ windows: [winState] });
+      }
+    }
+
+    // Merge closed windows from this session with ones from last session
+    if (lastSessionState._closedWindows) {
+      this._closedWindows = this._closedWindows.concat(lastSessionState._closedWindows);
+      this._capClosedWindows();
+    }
+
+    // Set data that persists between sessions
+    this._recentCrashes = lastSessionState.session &&
+                          lastSessionState.session.recentCrashes || 0;
+    this._sessionStartTime = lastSessionState.session &&
+                             lastSessionState.session.startTime ||
+                             this._sessionStartTime;
+
+    this._lastSessionState = null;
+  },
+
+  /**
+   * See if aWindow is usable for use when restoring a previous session via
+   * restoreLastSession. If usable, prepare it for use.
+   *
+   * @param aWindow
+   *        the window to inspect & prepare
+   * @returns [canUseWindow, canOverwriteTabs]
+   *          canUseWindow: can the window be used to restore into
+   *          canOverwriteTabs: all of the current tabs are home pages and we
+   *                            can overwrite them
+   */
+  _prepWindowToRestoreInto: function sss__prepWindowToRestoreInto(aWindow) {
+    if (!aWindow)
+      return [false, false];
+
+    // We might be able to overwrite the existing tabs instead of just adding
+    // the previous session's tabs to the end. This will be set if possible.
+    let canOverwriteTabs = false;
+
+    // Step 1 of processing:
+    // Inspect extData for Panorama identifiers. If found, then we want to
+    // inspect further. If there is a single group, then we can use this
+    // window. If there are multiple groups then we won't use this window.
+    let data = this.getWindowValue(aWindow, "tabview-group");
+    if (data) {
+      data = JSON.parse(data);
+
+      // Multiple keys means multiple groups, which means we don't want to use this window.
+      if (Object.keys(data).length > 1) {
+        return [false, false];
+      }
+      else {
+        // If there is only one group, then we want to ensure that its group id
+        // is 0. This is how Panorama forces group merging when new tabs are opened.
+        //XXXzpao This is a hack and the proper fix really belongs in Panorama.
+        let groupKey = Object.keys(data)[0];
+        if (groupKey !== "0") {
+          data["0"] = data[groupKey];
+          delete data[groupKey];
+          this.setWindowValue(aWindow, "tabview-groups", JSON.stringify(data));
+        }
+      }
+    }
+
+    // Step 2 of processing:
+    // If we're still here, then the window is usable. Look at the open tabs in
+    // comparison to home pages. If all the tabs are home pages then we'll end
+    // up overwriting all of them. Otherwise we'll just close the tabs that
+    // match home pages.
+    let homePages = aWindow.getHomePage();
+    let removableTabs = [];
+    let tabbrowser = aWindow.getBrowser();
+    let normalTabsLen = tabbrowser.tabs.length - tabbrowser._numPinnedTabs;
+    for (let i = 0; i < tabbrowser.tabs.length; i++) {
+      let tab = tabbrowser.tabs[i];
+      if (homePages.includes(tab.linkedBrowser.currentURI.spec)) {
+        removableTabs.push(tab);
+      }
+    }
+
+    if (tabbrowser.tabs.length == removableTabs.length) {
+      canOverwriteTabs = true;
+    }
+    else {
+      // If we're not overwriting all of the tabs, then close the home tabs.
+      for (let i = removableTabs.length - 1; i >= 0; i--) {
+        tabbrowser.removeTab(removableTabs.pop(), { animate: false });
+      }
+    }
+
+    return [true, canOverwriteTabs];
+  },
+
+/* ........ Saving Functionality .............. */
+
+  /**
+   * Store all session data for a window
+   * @param aWindow
+   *        Window reference
+   */
+  _saveWindowHistory: function sss_saveWindowHistory(aWindow) {
+    var tabbrowser = aWindow.getBrowser();
+    var tabs = tabbrowser.tabs;
+    var tabsData = this._windows[aWindow.__SSi].tabs = [];
+
+    for (var i = 0; i < tabs.length; i++)
+      tabsData.push(this._collectTabData(tabs[i]));
+
+    this._windows[aWindow.__SSi].selected = tabbrowser.mTabBox.selectedIndex + 1;
+  },
+
+  /**
+   * Collect data related to a single tab
+   * @param aTab
+   *        tabbrowser tab
+   * @param aFullData
+   *        always return privacy sensitive data (use with care)
+   * @returns object
+   */
+  _collectTabData: function sss_collectTabData(aTab, aFullData) {
+    var tabData = { entries: [] };
+    var browser = aTab.linkedBrowser;
+
+    if (!browser || !browser.currentURI)
+      // can happen when calling this function right after .addTab()
+      return tabData;
+    else if (browser.__SS_data &&
+             browser.__SS_restoreState == TAB_STATE_NEEDS_RESTORE) {
+      // use the data to be restored when the tab hasn't been completely loaded
+      tabData = browser.__SS_data;
+      if (aTab.pinned)
+        tabData.pinned = true;
+      else
+        delete tabData.pinned;
+      tabData.hidden = aTab.hidden;
+
+      // If __SS_extdata is set then we'll use that since it might be newer.
+      if (aTab.__SS_extdata)
+        tabData.extData = aTab.__SS_extdata;
+      // If it exists but is empty then a key was likely deleted. In that case just
+      // delete extData.
+      if (tabData.extData && !Object.keys(tabData.extData).length)
+        delete tabData.extData;
+      return tabData;
+    }
+
+    var history = null;
+    try {
+      history = browser.sessionHistory;
+    }
+    catch (ex) { } // this could happen if we catch a tab during (de)initialization
+
+    // XXXzeniko anchor navigation doesn't reset __SS_data, so we could reuse
+    //           data even when we shouldn't (e.g. Back, different anchor)
+    if (history && browser.__SS_data &&
+        browser.__SS_data.entries[history.index] &&
+        browser.__SS_data.entries[history.index].url == browser.currentURI.spec &&
+        history.index < this._sessionhistory_max_entries - 1 && !aFullData) {
+      tabData = browser.__SS_data;
+      tabData.index = history.index + 1;
+    }
+    else if (history && history.count > 0) {
+      try {
+        for (var j = 0; j < history.count; j++) {
+          let entry = this._serializeHistoryEntry(history.getEntryAtIndex(j),
+                                                  aFullData, aTab.pinned);
+          tabData.entries.push(entry);
+        }
+        // If we make it through the for loop, then we're ok and we should clear
+        // any indicator of brokenness.
+        delete aTab.__SS_broken_history;
+      }
+      catch (ex) {
+        // In some cases, getEntryAtIndex will throw. This seems to be due to
+        // history.count being higher than it should be. By doing this in a
+        // try-catch, we'll update history to where it breaks, assert for
+        // non-release builds, and still save sessionstore.js. We'll track if
+        // we've shown the assert for this tab so we only show it once.
+        // cf. bug 669196.
+        if (!aTab.__SS_broken_history) {
+          // First Focus the window & tab we're having trouble with.
+          aTab.ownerDocument.defaultView.focus();
+          aTab.ownerDocument.defaultView.getBrowser().selectedTab = aTab;
+          debug("SessionStore failed gathering complete history " +
+                "for the focused window/tab. See bug 669196.");
+          aTab.__SS_broken_history = true;
+        }
+      }
+      tabData.index = history.index + 1;
+
+      // make sure not to cache privacy sensitive data which shouldn't get out
+      if (!aFullData)
+        browser.__SS_data = tabData;
+    }
+    else if (browser.currentURI.spec != "about:blank" ||
+             browser.contentDocument.body.hasChildNodes()) {
+      tabData.entries[0] = { url: browser.currentURI.spec,
+                             triggeringPrincipal_base64: Utils.SERIALIZED_SYSTEMPRINCIPAL };
+      tabData.index = 1;
+    }
+
+    // If there is a userTypedValue set, then either the user has typed something
+    // in the URL bar, or a new tab was opened with a URI to load. userTypedClear
+    // is used to indicate whether the tab was in some sort of loading state with
+    // userTypedValue.
+    if (browser.userTypedValue) {
+      tabData.userTypedValue = browser.userTypedValue;
+      tabData.userTypedClear = browser.userTypedClear;
+    } else {
+      delete tabData.userTypedValue;
+      delete tabData.userTypedClear;
+    }
+
+    var disallow = [];
+    for (var i = 0; i < CAPABILITIES.length; i++)
+      if (!browser.docShell["allow" + CAPABILITIES[i]])
+        disallow.push(CAPABILITIES[i]);
+    if (disallow.length > 0)
+      tabData.disallow = disallow.join(",");
+    else if (tabData.disallow)
+      delete tabData.disallow;
+
+    tabData.attributes = {};
+    for (let name in this.xulAttributes) {
+      if (aTab.hasAttribute(name))
+        tabData.attributes[name] = aTab.getAttribute(name);
+    }
+
+    if (aTab.__SS_extdata)
+      tabData.extData = aTab.__SS_extdata;
+    else if (tabData.extData)
+      delete tabData.extData;
+
+    if (history && browser.docShell instanceof Ci.nsIDocShell)
+      this._serializeSessionStorage(tabData, history, browser.docShell, aFullData,
+                                    false);
+
+    return tabData;
+  },
+
+  /**
+   * Get an object that is a serialized representation of a History entry
+   * Used for data storage
+   * @param aEntry
+   *        nsISHEntry instance
+   * @param aFullData
+   *        always return privacy sensitive data (use with care)
+   * @param aIsPinned
+   *        the tab is pinned and should be treated differently for privacy
+   * @returns object
+   */
+  _serializeHistoryEntry:
+    function sss_serializeHistoryEntry(aEntry, aFullData, aIsPinned) {
+    var entry = { url: aEntry.URI.spec,
+                  triggeringPrincipal_base64: Utils.SERIALIZED_SYSTEMPRINCIPAL };
+
+    if (aEntry.title && aEntry.title != entry.url) {
+      entry.title = aEntry.title;
+    }
+    if (aEntry.isSubFrame) {
+      entry.subframe = true;
+    }
+    if (!(aEntry instanceof Ci.nsISHEntry)) {
+      return entry;
+    }
+
+    var cacheKey = aEntry.cacheKey;
+    if (cacheKey && cacheKey instanceof Ci.nsISupportsPRUint32 &&
+        cacheKey.data != 0) {
+      // XXXbz would be better to have cache keys implement
+      // nsISerializable or something.
+      entry.cacheKey = cacheKey.data;
+    }
+    entry.ID = aEntry.ID;
+    entry.docshellUUID = aEntry.docshellID.toString();
+
+    if (aEntry.referrerURI)
+      entry.referrer = aEntry.referrerURI.spec;
+
+    if (aEntry.contentType)
+      entry.contentType = aEntry.contentType;
+
+    var x = {}, y = {};
+    aEntry.getScrollPosition(x, y);
+    if (x.value != 0 || y.value != 0)
+      entry.scroll = x.value + "," + y.value;
+
+    try {
+      var prefPostdata = this._prefBranch.getIntPref("sessionstore.postdata");
+      if (aEntry.postData && (aFullData || prefPostdata &&
+            this._checkPrivacyLevel(aEntry.URI.schemeIs("https"), aIsPinned))) {
+        aEntry.postData.QueryInterface(Ci.nsISeekableStream)
+                       .seek(Ci.nsISeekableStream.NS_SEEK_SET, 0);
+        var stream = Cc["@mozilla.org/binaryinputstream;1"]
+                       .createInstance(Ci.nsIBinaryInputStream);
+        stream.setInputStream(aEntry.postData);
+        var postBytes = stream.readByteArray(stream.available());
+        var postdata = String.fromCharCode.apply(null, postBytes);
+        if (aFullData || prefPostdata == -1 ||
+            postdata.replace(/^(Content-.*\r\n)+(\r\n)*/, "").length <=
+              prefPostdata) {
+          // We can stop doing base64 encoding once our serialization into JSON
+          // is guaranteed to handle all chars in strings, including embedded
+          // nulls.
+          entry.postdata_b64 = btoa(postdata);
+        }
+      }
+    }
+    catch (ex) { debug(ex); } // POSTDATA is tricky - especially since some extensions don't get it right
+
+    // Collect triggeringPrincipal data for the current history entry.
+    // Please note that before Bug 1297338 there was no concept of a
+    // principalToInherit. To remain backward/forward compatible we
+    // serialize the principalToInherit as triggeringPrincipal_b64.
+    // Once principalToInherit is well established (within Gecko 55)
+    // we can update this code, remove triggeringPrincipal_b64 and
+    // just keep triggeringPrincipal_base64 as well as
+    // principalToInherit_base64.
+    if (aEntry.principalToInherit) {
+      try {
+        let principalToInherit = Utils.serializePrincipal(aEntry.principalToInherit);
+        if (principalToInherit) {
+          entry.triggeringPrincipal_b64 = principalToInherit;
+          entry.principalToInherit_base64 = principalToInherit;
+        }
+      } catch (e) {
+        debug(e);
+      }
+    }
+
+    if (aEntry.triggeringPrincipal) {
+      try {
+        let triggeringPrincipal = Utils.serializePrincipal(aEntry.triggeringPrincipal);
+        if (triggeringPrincipal) {
+          entry.triggeringPrincipal_base64 = triggeringPrincipal;
+        }
+      } catch (e) {
+        debug(e);
+      }
+    }
+
+    entry.docIdentifier = aEntry.BFCacheEntry.ID;
+
+    if (aEntry.stateData) {
+      entry.structuredCloneState = aEntry.stateData.getDataAsBase64();
+      entry.structuredCloneVersion = aEntry.stateData.formatVersion;
+    }
+
+    if (!(aEntry instanceof Ci.nsISHContainer)) {
+      return entry;
+    }
+
+    if (aEntry.childCount > 0) {
+      entry.children = [];
+      for (var i = 0; i < aEntry.childCount; i++) {
+        var child = aEntry.GetChildAt(i);
+        if (child) {
+          entry.children.push(this._serializeHistoryEntry(child, aFullData, aIsPinned));
+        }
+        else { // to maintain the correct frame order, insert a dummy entry
+          entry.children.push({ url: "about:blank",
+                                triggeringPrincipal_base64: Utils.SERIALIZED_SYSTEMPRINCIPAL});
+        }
+        // don't try to restore framesets containing wyciwyg URLs (cf. bug 424689 and bug 450595)
+        if (/^wyciwyg:\/\//.test(entry.children[i].url)) {
+          delete entry.children;
+          break;
+        }
+      }
+    }
+
+    return entry;
+  },
+
+  /**
+   * Updates all sessionStorage "super cookies"
+   * @param aTabData
+   *        The data object for a specific tab
+   * @param aHistory
+   *        That tab's session history
+   * @param aDocShell
+   *        That tab's docshell (containing the sessionStorage)
+   * @param aFullData
+   *        always return privacy sensitive data (use with care)
+   * @param aIsPinned
+   *        the tab is pinned and should be treated differently for privacy
+   */
+  _serializeSessionStorage:
+    function sss_serializeSessionStorage(aTabData, aHistory, aDocShell, aFullData, aIsPinned) {
+    let storageData = {};
+    let hasContent = false;
+
+    for (let i = 0; i < aHistory.count; i++) {
+      let principal;
+      try {
+        let uri = aHistory.getEntryAtIndex(i).URI;
+        principal = SecMan.getDocShellCodebasePrincipal(uri, aDocShell);
+      }
+      catch (ex) {
+        // Chances are that this is getEntryAtIndex throwing, as seen in bug 669196.
+        // We've already asserted in _collectTabData, so we won't show that again.
+        continue;
+      }
+
+      // sessionStorage is saved per principal (cf. nsGlobalWindow::GetSessionStorage)
+      let origin;
+      try {
+        origin = principal.origin;
+      }
+      catch (ex) {
+        origin = principal.URI.spec;
+      }
+
+      if (storageData[origin])
+        continue;
+
+      let isHTTPS = principal.URI && principal.URI.schemeIs("https");
+      if (!(aFullData || this._checkPrivacyLevel(isHTTPS, aIsPinned)))
+        continue;
+
+      let storage, storageItemCount = 0;
+
+      let window = aDocShell.QueryInterface(Ci.nsIInterfaceRequestor)
+                            .getInterface(Ci.nsIDOMWindow);
+      try {
+        let storageManager = aDocShell.QueryInterface(Ci.nsIDOMStorageManager);
+        storage = storageManager.getStorage(window, principal);
+
+        // See Bug 1232955 - storage.length can throw, catch that failure here inside the try.
+        if (storage)
+          storageItemCount = storage.length;
+      }
+      catch (ex) { /* sessionStorage might throw if it's turned off, see bug 458954 */ }
+
+      if (storageItemCount == 0)
+        continue;
+
+      let data = storageData[origin] = {};
+
+      for (let j = 0; j < storageItemCount; j++) {
+        try {
+          let key = storage.key(j);
+          data[key] = storage.getItem(key);
+        }
+        catch (ex) { /* XXXzeniko this currently throws for secured items (cf. bug 442048) */ }
+      }
+      hasContent = true;
+    }
+
+    if (hasContent)
+      aTabData.storage = storageData;
+  },
+
+  /**
+   * go through all tabs and store the current scroll positions
+   * and innerHTML content of WYSIWYG editors
+   * @param aWindow
+   *        Window reference
+   */
+  _updateTextAndScrollData: function sss_updateTextAndScrollData(aWindow) {
+    var browsers = aWindow.getBrowser().browsers;
+    for (var i = 0; i < browsers.length; i++) {
+      try {
+        var tabData = this._windows[aWindow.__SSi].tabs[i];
+        if (browsers[i].__SS_data &&
+            browsers[i].__SS_restoreState == TAB_STATE_NEEDS_RESTORE)
+          continue; // ignore incompletely initialized tabs
+        this._updateTextAndScrollDataForTab(aWindow, browsers[i], tabData);
+      }
+      catch (ex) { debug(ex); } // get as much data as possible, ignore failures (might succeed the next time)
+    }
+  },
+
+  /**
+   * go through all frames and store the current scroll positions
+   * and innerHTML content of WYSIWYG editors
+   * @param aWindow
+   *        Window reference
+   * @param aBrowser
+   *        single browser reference
+   * @param aTabData
+   *        tabData object to add the information to
+   * @param aFullData
+   *        always return privacy sensitive data (use with care)
+   */
+  _updateTextAndScrollDataForTab:
+    function sss_updateTextAndScrollDataForTab(aWindow, aBrowser, aTabData, aFullData) {
+    var tabIndex = (aTabData.index || aTabData.entries.length) - 1;
+    // entry data needn't exist for tabs just initialized with an incomplete session state
+    if (!aTabData.entries[tabIndex])
+      return;
+
+    let selectedPageStyle = aBrowser.markupDocumentViewer.authorStyleDisabled ? "_nostyle" :
+                            this._getSelectedPageStyle(aBrowser.contentWindow);
+    if (selectedPageStyle)
+      aTabData.pageStyle = selectedPageStyle;
+    else if (aTabData.pageStyle)
+      delete aTabData.pageStyle;
+
+    this._updateTextAndScrollDataForFrame(aWindow, aBrowser.contentWindow,
+                                          aTabData.entries[tabIndex],
+                                          aFullData,
+                                          !!aTabData.pinned);
+    if (aBrowser.currentURI.spec == "about:config")
+      aTabData.entries[tabIndex].formdata = {
+        "#textbox": aBrowser.contentDocument.getElementById("textbox").value
+      };
+  },
+
+  /**
+   * go through all subframes and store all form data, the current
+   * scroll positions and innerHTML content of WYSIWYG editors
+   * @param aWindow
+   *        Window reference
+   * @param aContent
+   *        frame reference
+   * @param aData
+   *        part of a tabData object to add the information to
+   * @param aFullData
+   *        always return privacy sensitive data (use with care)
+   * @param aIsPinned
+   *        the tab is pinned and should be treated differently for privacy
+   */
+  _updateTextAndScrollDataForFrame:
+    function sss_updateTextAndScrollDataForFrame(aWindow, aContent, aData,
+                                                 aFullData, aIsPinned) {
+    for (var i = 0; i < aContent.frames.length; i++) {
+      if (aData.children && aData.children[i])
+        this._updateTextAndScrollDataForFrame(aWindow, aContent.frames[i],
+                                              aData.children[i],
+                                              aFullData, aIsPinned);
+    }
+    var isHTTPS = this._getURIFromString((aContent.parent || aContent).
+                                         document.location.href).schemeIs("https");
+    if (aFullData || this._checkPrivacyLevel(isHTTPS, aIsPinned) ||
+        aContent.top.document.location.href == "about:sessionrestore") {
+      let formData = this._collectFormDataForFrame(aContent.document);
+      if (formData)
+        aData.formdata = formData;
+      else if (aData.formdata)
+        delete aData.formdata;
+
+      // designMode is undefined e.g. for XUL documents (as about:config)
+      if ((aContent.document.designMode || "") == "on") {
+        if (aData.innerHTML === undefined && !aFullData) {
+          // we get no "input" events from iframes - listen for keypress here
+          aContent.addEventListener("keypress", this.saveStateDelayed.bind(this, aWindow, 3000), true);
+        }
+        aData.innerHTML = aContent.document.body.innerHTML;
+      }
+    }
+
+    // get scroll position from nsIDOMWindowUtils, since it allows avoiding a
+    // flush of layout
+    let domWindowUtils = aContent.QueryInterface(Ci.nsIInterfaceRequestor)
+                                 .getInterface(Ci.nsIDOMWindowUtils);
+    let scrollX = {}, scrollY = {};
+    domWindowUtils.getScrollXY(false, scrollX, scrollY);
+    aData.scroll = scrollX.value + "," + scrollY.value;
+  },
+
+  /**
+   * determine the title of the currently enabled style sheet (if any)
+   * and recurse through the frameset if necessary
+   * @param   aContent is a frame reference
+   * @returns the title style sheet determined to be enabled (empty string if none)
+   */
+  _getSelectedPageStyle: function sss_getSelectedPageStyle(aContent) {
+    const forScreen = /(?:^|,)\s*(?:all|screen)\s*(?:,|$)/i;
+    for (let i = 0; i < aContent.document.styleSheets.length; i++) {
+      let ss = aContent.document.styleSheets[i];
+      let media = ss.media.mediaText;
+      if (!ss.disabled && ss.title && (!media || forScreen.test(media)))
+        return ss.title
+    }
+    for (let i = 0; i < aContent.frames.length; i++) {
+      let selectedPageStyle = this._getSelectedPageStyle(aContent.frames[i]);
+      if (selectedPageStyle)
+        return selectedPageStyle;
+    }
+    return "";
+  },
+
+  /**
+   * collect the state of all form elements
+   * @param aDocument
+   *        document reference
+   */
+  _collectFormDataForFrame: function sss_collectFormDataForFrame(aDocument) {
+    let formNodes = aDocument.evaluate(XPathGenerator.restorableFormNodes, aDocument,
+                                       XPathGenerator.resolveNS,
+                                       aDocument.defaultView.XPathResult.UNORDERED_NODE_ITERATOR_TYPE, null);
+    let node = formNodes.iterateNext();
+    if (!node)
+      return null;
+
+    const MAX_GENERATED_XPATHS = 100;
+    let generatedCount = 0;
+
+    let data = {};
+    do {
+      let nId = node.id;
+      let hasDefaultValue = true;
+      let value;
+
+      // Only generate a limited number of XPath expressions for perf reasons (cf. bug 477564)
+      if (!nId && generatedCount > MAX_GENERATED_XPATHS)
+        continue;
+
+      if (ChromeUtils.getClassName(node) === "HTMLInputElement" ||
+          ChromeUtils.getClassName(node) === "HTMLTextAreaElement") {
+        switch (node.type) {
+          case "checkbox":
+          case "radio":
+            value = node.checked;
+            hasDefaultValue = value == node.defaultChecked;
+            break;
+          case "file":
+            value = { type: "file", fileList: node.mozGetFileNameArray() };
+            hasDefaultValue = !value.fileList.length;
+            break;
+          default: // text, textarea
+            value = node.value;
+            hasDefaultValue = value == node.defaultValue;
+            break;
+        }
+      }
+      else if (!node.multiple) {
+        // <select>s without the multiple attribute are hard to determine the
+        // default value, so assume we don't have the default.
+        hasDefaultValue = false;
+        value = node.selectedIndex;
+      }
+      else {
+        // <select>s with the multiple attribute are easier to determine the
+        // default value since each <option> has a defaultSelected
+        let options = Array.from(node.options, function(aOpt, aIx) {
+          let oSelected = aOpt.selected;
+          hasDefaultValue = hasDefaultValue && (oSelected == aOpt.defaultSelected);
+          return oSelected ? aIx : -1;
+        });
+        value = options.filter(aIx => aIx >= 0);
+      }
+      // In order to reduce XPath generation (which is slow), we only save data
+      // for form fields that have been changed. (cf. bug 537289)
+      if (!hasDefaultValue) {
+        if (nId) {
+          data["#" + nId] = value;
+        }
+        else {
+          generatedCount++;
+          data[XPathGenerator.generate(node)] = value;
+        }
+      }
+
+    } while ((node = formNodes.iterateNext()));
+
+    return data;
+  },
+
+  /**
+   * extract the base domain from a history entry and its children
+   * @param aEntry
+   *        the history entry, serialized
+   * @param aHosts
+   *        the hash that will be used to store hosts eg, { hostname: true }
+   * @param aCheckPrivacy
+   *        should we check the privacy level for https
+   * @param aIsPinned
+   *        is the entry we're evaluating for a pinned tab; used only if
+   *        aCheckPrivacy
+   */
+  _extractHostsForCookiesFromEntry:
+    function sss__extractHostsForCookiesFromEntry(aEntry, aHosts, aCheckPrivacy, aIsPinned) {
+
+    if (aEntry.children) {
+      aEntry.children.forEach(function(entry) {
+        this._extractHostsForCookiesFromEntry(entry, aHosts, aCheckPrivacy, aIsPinned);
+      }, this);
+    }
+  },
+
+  /**
+   * extract the base domain from a host & scheme
+   * @param aHost
+   *        the host of a uri (usually via nsIURI.host)
+   * @param aScheme
+   *        the scheme of a uri (usually via nsIURI.scheme)
+   * @param aHosts
+   *        the hash that will be used to store hosts eg, { hostname: true }
+   * @param aCheckPrivacy
+   *        should we check the privacy level for https
+   * @param aIsPinned
+   *        is the entry we're evaluating for a pinned tab; used only if
+   *        aCheckPrivacy
+   */
+  _extractHostsForCookiesFromHostScheme:
+    function sss__extractHostsForCookiesFromHostScheme(aHost, aScheme, aHosts, aCheckPrivacy, aIsPinned) {
+    // host and scheme may not be set (for about: urls for example), in which
+    // case testing scheme will be sufficient.
+    if (/https?/.test(aScheme) && !aHosts[aHost] &&
+        (!aCheckPrivacy ||
+         this._checkPrivacyLevel(aScheme == "https", aIsPinned))) {
+      // By setting this to true or false, we can determine when looking at
+      // the host in _updateCookies if we should check for privacy.
+      aHosts[aHost] = aIsPinned;
+    }
+    else if (aScheme == "file") {
+      aHosts[aHost] = true;
+    }
+  },
+
+  /**
+   * Serialize cookie data
+   * @param aWindows
+   *        JS object containing window data references
+   *        { id: winData, etc. }
+   */
+  _updateCookies: function sss_updateCookies(aWindows) {
+    var jscookies = {};
+    // MAX_EXPIRY should be 2^63-1, but JavaScript can't handle that precision
+    var MAX_EXPIRY = Math.pow(2, 62);
+
+    for (let window of aWindows) {
+      window.cookies = [];
+
+      // Collect all hosts for the current window.
+      let hosts = {};
+      window.tabs.forEach(function(tab) {
+        tab.entries.forEach(function(entry) {
+          this._extractHostsForCookiesFromEntry(entry, hosts, true, tab.pinned);
+        }, this);
+      }, this);
+
+      for (var [host, isPinned] of Object.entries(hosts)) {
+        try {
+          var list = Services.cookies.getCookiesFromHost(host, {});
+          while (list.hasMoreElements()) {
+            var cookie = list.getNext().QueryInterface(Ci.nsICookie2);
+            // window._hosts will only have hosts with the right privacy rules,
+            // so there is no need to do anything special with this call to
+            // _checkPrivacyLevel.
+            if (cookie.isSession && this._checkPrivacyLevel(cookie.isSecure, isPinned)) {
+              // use the cookie's host, path, and name as keys into a hash,
+              // to make sure we serialize each cookie only once
+
+              // lazily build up a 3-dimensional hash, with
+              // host, path, and name as keys
+              if (!jscookies[cookie.host])
+                jscookies[cookie.host] = {};
+              if (!jscookies[cookie.host][cookie.path])
+                jscookies[cookie.host][cookie.path] = {};
+
+              if (!jscookies[cookie.host][cookie.path][cookie.name]) {
+                var jscookie = { "host": cookie.host, "value": cookie.value };
+                // only add attributes with non-default values (saving a few bits)
+                if (cookie.path)
+                  jscookie.path = cookie.path;
+                if (cookie.name)
+                  jscookie.name = cookie.name;
+                if (cookie.isSecure)
+                  jscookie.secure = true;
+                if (cookie.isHttpOnly)
+                  jscookie.httponly = true;
+                if (cookie.expiry < MAX_EXPIRY)
+                  jscookie.expiry = cookie.expiry;
+                if (cookie.originAttributes)
+                  jscookie.originAttributes = cookie.originAttributes;
+
+                jscookies[cookie.host][cookie.path][cookie.name] = jscookie;
+              }
+            window.cookies.push(jscookies[cookie.host][cookie.path][cookie.name]);
+            }
+          }
+        }
+        catch (ex) {
+          debug("getCookiesFromHost failed. Host: " + host);
+        }
+      }
+
+      // don't include empty cookie sections
+      if (!window.cookies.length)
+        delete window.cookies;
+    }
+  },
+
+  /**
+   * Store window dimensions, visibility, sidebar
+   * @param aWindow
+   *        Window reference
+   */
+  _updateWindowFeatures: function sss_updateWindowFeatures(aWindow) {
+    var winData = this._windows[aWindow.__SSi];
+
+    for (var aAttr in WINDOW_ATTRIBUTES)
+      winData[aAttr] = this._getWindowDimension(aWindow, aAttr);
+
+    var hidden = WINDOW_HIDEABLE_FEATURES.filter(function(aItem) {
+      return aWindow[aItem] && !aWindow[aItem].visible;
+    });
+    if (hidden.length != 0)
+      winData.hidden = hidden.join(",");
+    else if (winData.hidden)
+      delete winData.hidden;
+
+    var sidebar = aWindow.document.getElementById("sidebar-box").getAttribute("sidebarcommand");
+    if (sidebar)
+      winData.sidebar = sidebar;
+    else if (winData.sidebar)
+      delete winData.sidebar;
+  },
+
+  /**
+   * serialize session data as Ini-formatted string
+   * @param aUpdateAll
+   *        Bool update all windows
+   * @returns string
+   */
+  _getCurrentState: function sss_getCurrentState(aUpdateAll) {
+    this._handleClosedWindows();
+
+    var activeWindow = this._getMostRecentBrowserWindow();
+
+    if (this._loadState == STATE_RUNNING) {
+      // update the data for all windows with activities since the last save operation
+      this._forEachBrowserWindow(function(aWindow) {
+        if (!this._isWindowLoaded(aWindow)) // window data is still in _statesToRestore
+          return;
+        if (aUpdateAll || DirtyWindows.has(aWindow) || aWindow == activeWindow) {
+          this._collectWindowData(aWindow);
+        }
+        else { // always update the window features (whose change alone never triggers a save operation)
+          this._updateWindowFeatures(aWindow);
+        }
+      });
+      DirtyWindows.clear();
+    }
+
+    // collect the data for all windows
+    var total = [], ids = [];
+    var nonPopupCount = 0;
+    var ix;
+    for (ix in this._windows) {
+      if (this._windows[ix]._restoring) // window data is still in _statesToRestore
+        continue;
+      total.push(this._windows[ix]);
+      ids.push(ix);
+      if (!this._windows[ix].isPopup)
+        nonPopupCount++;
+    }
+    this._updateCookies(total);
+
+    // collect the data for all windows yet to be restored
+    for (ix in this._statesToRestore) {
+      for (let winData of this._statesToRestore[ix].windows) {
+        total.push(winData);
+        if (!winData.isPopup)
+          nonPopupCount++;
+      }
+    }
+
+    // shallow copy this._closedWindows to preserve current state
+    let lastClosedWindowsCopy = this._closedWindows.slice();
+
+    // If no non-popup browser window remains open, return the state of the last
+    // closed window(s). We only want to do this when we're actually "ending"
+    // the session.
+    //XXXzpao We should do this for _restoreLastWindow == true, but that has
+    //        its own check for popups. c.f. bug 597619
+    if (AppConstants.platform != "macosx" && 
+        nonPopupCount == 0 && lastClosedWindowsCopy.length > 0 &&
+        this._loadState == STATE_QUITTING) {
+      // prepend the last non-popup browser window, so that if the user loads more tabs
+      // at startup we don't accidentally add them to a popup window
+      do {
+        total.unshift(lastClosedWindowsCopy.shift())
+      } while (total[0].isPopup)
+    }
+
+    if (activeWindow) {
+      this.activeWindowSSiCache = activeWindow.__SSi || "";
+    }
+    ix = ids.indexOf(this.activeWindowSSiCache);
+    // We don't want to restore focus to a minimized window.
+    if (ix != -1 && total[ix].sizemode == "minimized")
+      ix = -1;
+
+    let session = {
+      state: this._loadState == STATE_RUNNING ? STATE_RUNNING_STR : STATE_STOPPED_STR,
+      lastUpdate: Date.now(),
+      startTime: this._sessionStartTime,
+      recentCrashes: this._recentCrashes
+    };
+
+    return {
+      windows: total,
+      selectedWindow: ix + 1,
+      _closedWindows: lastClosedWindowsCopy,
+      session: session
+    };
+  },
+
+  /**
+   * serialize session data for a window
+   * @param aWindow
+   *        Window reference
+   * @returns string
+   */
+  _getWindowState: function sss_getWindowState(aWindow) {
+    if (!this._isWindowLoaded(aWindow))
+      return this._statesToRestore[aWindow.__SS_restoreID];
+
+    if (this._loadState == STATE_RUNNING) {
+      this._collectWindowData(aWindow);
+    }
+
+    let windows = [this._windows[aWindow.__SSi]];
+    this._updateCookies(windows);
+
+    return { windows: windows };
+  },
+
+  _collectWindowData: function sss_collectWindowData(aWindow) {
+    if (!this._isWindowLoaded(aWindow))
+      return;
+
+    // update the internal state data for this window
+    this._saveWindowHistory(aWindow);
+    this._updateTextAndScrollData(aWindow);
+    this._updateWindowFeatures(aWindow);
+
+    // Make sure we keep __SS_lastSessionWindowID around for cases like entering
+    // or leaving PB mode.
+    if (aWindow.__SS_lastSessionWindowID)
+      this._windows[aWindow.__SSi].__lastSessionWindowID =
+        aWindow.__SS_lastSessionWindowID;
+
+    DirtyWindows.remove(aWindow);
+  },
+
+/* ........ Restoring Functionality .............. */
+
+  /**
+   * restore features to a single window
+   * @param aWindow
+   *        Window reference
+   * @param aState
+   *        JS object or its eval'able source
+   * @param aOverwriteTabs
+   *        bool overwrite existing tabs w/ new ones
+   * @param aFollowUp
+   *        bool this isn't the restoration of the first window
+   */
+  restoreWindow: function sss_restoreWindow(aWindow, aState, aOverwriteTabs, aFollowUp) {
+    if (!aFollowUp) {
+      this.windowToFocus = aWindow;
+    }
+    // initialize window if necessary
+    if (aWindow && (!aWindow.__SSi || !this._windows[aWindow.__SSi]))
+      this.onLoad(aWindow);
+
+    try {
+      var root = typeof aState == "string" ? JSON.parse(aState) : aState;
+      if (!root.windows[0]) {
+        this._sendRestoreCompletedNotifications();
+        return; // nothing to restore
+      }
+    }
+    catch (ex) { // invalid state object - don't restore anything
+      debug(ex);
+      this._sendRestoreCompletedNotifications();
+      return;
+    }
+
+    // We're not returning from this before we end up calling restoreHistoryPrecursor
+    // for this window, so make sure we send the SSWindowStateBusy event.
+    this._sendWindowStateEvent(aWindow, "Busy");
+
+    if (root._closedWindows)
+      this._closedWindows = root._closedWindows;
+
+    var winData;
+    if (!aState.selectedWindow || aState.selectedWindow > aState.windows.length) {
+      aState.selectedWindow = 0;
+    }
+    // open new windows for all further window entries of a multi-window session
+    // (unless they don't contain any tab data)
+    for (var w = 1; w < root.windows.length; w++) {
+      winData = root.windows[w];
+      if (winData && winData.tabs && winData.tabs[0]) {
+        var window = this._openWindowWithState({ windows: [winData] });
+        if (w == aState.selectedWindow - 1) {
+          this.windowToFocus = window;
+        }
+      }
+    }
+    winData = root.windows[0];
+    if (!winData.tabs) {
+      winData.tabs = [];
+    }
+    // don't restore a single blank tab when we've had an external
+    // URL passed in for loading at startup (cf. bug 357419)
+    else if (root._firstTabs && !aOverwriteTabs && winData.tabs.length == 1 &&
+             (!winData.tabs[0].entries || winData.tabs[0].entries.length == 0)) {
+      winData.tabs = [];
+    }
+
+    var tabbrowser = aWindow.getBrowser();
+    var openTabCount = aOverwriteTabs ? tabbrowser.browsers.length : -1;
+    var newTabCount = winData.tabs.length;
+    var tabs = [];
+
+    // disable smooth scrolling while adding, moving, removing and selecting tabs
+    var tabstrip = tabbrowser.tabContainer.arrowScrollbox;
+    var smoothScroll = tabstrip.smoothScroll;
+    tabstrip.smoothScroll = false;
+
+    // make sure that the selected tab won't be closed in order to
+    // prevent unnecessary flickering
+    if (aOverwriteTabs && tabbrowser.tabContainer.selectedIndex >= newTabCount)
+      tabbrowser.moveTabTo(tabbrowser.selectedTab, newTabCount - 1);
+
+    for (var t = 0; t < newTabCount; t++) {
+      tabs.push(t < openTabCount ?
+                tabbrowser.tabs[t] :
+                // Ftr, SeaMonkey doesn't support animation (yet).
+                tabbrowser.addTab("about:blank"));
+      // when resuming at startup: add additionally requested pages to the end
+      if (!aOverwriteTabs && root._firstTabs) {
+        tabbrowser.moveTabTo(tabs[t], t);
+      }
+    }
+
+    // If overwriting tabs, we want to reset each tab's "restoring" state. Since
+    // we're overwriting those tabs, they should no longer be restoring. The
+    // tabs will be rebuilt and marked if they need to be restored after loading
+    // state (in restoreHistoryPrecursor).
+    if (aOverwriteTabs) {
+      for (let i = 0; i < tabbrowser.tabs.length; i++) {
+        if (tabbrowser.browsers[i].__SS_restoreState)
+          this._resetTabRestoringState(tabbrowser.tabs[i]);
+      }
+    }
+
+    // We want to set up a counter on the window that indicates how many tabs
+    // in this window are unrestored. This will be used in restoreNextTab to
+    // determine if gRestoreTabsProgressListener should be removed from the window.
+    // If we aren't overwriting existing tabs, then we want to add to the existing
+    // count in case there are still tabs restoring.
+    if (!aWindow.__SS_tabsToRestore)
+      aWindow.__SS_tabsToRestore = 0;
+    if (aOverwriteTabs)
+      aWindow.__SS_tabsToRestore = newTabCount;
+    else
+      aWindow.__SS_tabsToRestore += newTabCount;
+
+    // We want to correlate the window with data from the last session, so
+    // assign another id if we have one. Otherwise clear so we don't do
+    // anything with it.
+    delete aWindow.__SS_lastSessionWindowID;
+    if (winData.__lastSessionWindowID)
+      aWindow.__SS_lastSessionWindowID = winData.__lastSessionWindowID;
+
+    // when overwriting tabs, remove all superflous ones
+    for (t = openTabCount - 1; t >= newTabCount; t--) {
+      tabbrowser.removeTab(tabbrowser.tabs[t]);
+    }
+
+    if (aOverwriteTabs) {
+      this.restoreWindowFeatures(aWindow, winData);
+      delete this._windows[aWindow.__SSi].extData;
+    }
+    if (winData.cookies) {
+      this.restoreCookies(winData.cookies);
+    }
+    if (winData.extData) {
+      if (!this._windows[aWindow.__SSi].extData) {
+        this._windows[aWindow.__SSi].extData = {};
+      }
+      for (var key in winData.extData) {
+        this._windows[aWindow.__SSi].extData[key] = winData.extData[key];
+      }
+    }
+    if (aOverwriteTabs || root._firstTabs) {
+      this._windows[aWindow.__SSi]._closedTabs = winData._closedTabs || [];
+    }
+
+    this.restoreHistoryPrecursor(aWindow, tabs, winData.tabs,
+      (aOverwriteTabs ? (parseInt(winData.selected) || 1) : 0), 0, 0);
+
+    // set smoothScroll back to the original value
+    tabstrip.smoothScroll = smoothScroll;
+
+    this._sendRestoreCompletedNotifications();
+  },
+
+  /**
+   * Manage history restoration for a window
+   * @param aWindow
+   *        Window to restore the tabs into
+   * @param aTabs
+   *        Array of tab references
+   * @param aTabData
+   *        Array of tab data
+   * @param aSelectTab
+   *        Index of selected tab
+   * @param aIx
+   *        Index of the next tab to check readyness for
+   * @param aCount
+   *        Counter for number of times delaying b/c browser or history aren't ready
+   */
+  restoreHistoryPrecursor:
+    function sss_restoreHistoryPrecursor(aWindow, aTabs, aTabData, aSelectTab, aIx, aCount) {
+    var tabbrowser = aWindow.getBrowser();
+
+    // make sure that all browsers and their histories are available
+    // - if one's not, resume this check in 100ms (repeat at most 10 times)
+    for (var t = aIx; t < aTabs.length; t++) {
+      try {
+        if (!tabbrowser.getBrowserForTab(aTabs[t]).webNavigation.sessionHistory) {
+          throw new Error();
+        }
+      }
+      catch (ex) { // in case browser or history aren't ready yet
+        if (aCount < 10) {
+          var restoreHistoryFunc = function(self) {
+            self.restoreHistoryPrecursor(aWindow, aTabs, aTabData, aSelectTab, aIx, aCount + 1);
+          }
+          aWindow.setTimeout(restoreHistoryFunc, 100, this);
+          return;
+        }
+      }
+    }
+
+    if (!this._isWindowLoaded(aWindow)) {
+      // from now on, the data will come from the actual window
+      delete this._statesToRestore[aWindow.__SS_restoreID];
+      delete aWindow.__SS_restoreID;
+      delete this._windows[aWindow.__SSi]._restoring;
+
+      // It's important to set the window state to dirty so that
+      // we collect their data for the first time when saving state.
+      DirtyWindows.add(aWindow);
+    }
+
+    if (aTabs.length == 0) {
+      // this is normally done in restoreHistory() but as we're returning early
+      // here we need to take care of it.
+      this._sendWindowStateEvent(aWindow, "Ready");
+      return;
+    }
+
+    if (aTabs.length > 1) {
+      // Load hidden tabs last, by pushing them to the end of the list
+      let unhiddenTabs = aTabs.length;
+      for (let t = 0; t < unhiddenTabs; ) {
+        if (aTabData[t].hidden) {
+          aTabs = aTabs.concat(aTabs.splice(t, 1));
+          aTabData = aTabData.concat(aTabData.splice(t, 1));
+          if (aSelectTab > t)
+            --aSelectTab;
+          --unhiddenTabs;
+          continue;
+        }
+        ++t;
+      }
+
+      // Determine if we can optimize & load visible tabs first
+      let maxVisibleTabs = Math.ceil(tabbrowser.tabContainer.arrowScrollbox.scrollClientSize /
+                                     aTabs[unhiddenTabs - 1].getBoundingClientRect().width);
+
+      // make sure we restore visible tabs first, if there are enough
+      if (maxVisibleTabs < unhiddenTabs && aSelectTab > 1) {
+        let firstVisibleTab = 0;
+        if (unhiddenTabs - maxVisibleTabs > aSelectTab) {
+          // aSelectTab is leftmost since we scroll to it when possible
+          firstVisibleTab = aSelectTab - 1;
+        } else {
+          // aSelectTab is rightmost or no more room to scroll right
+          firstVisibleTab = unhiddenTabs - maxVisibleTabs;
+        }
+        aTabs = aTabs.splice(firstVisibleTab, maxVisibleTabs).concat(aTabs);
+        aTabData = aTabData.splice(firstVisibleTab, maxVisibleTabs).concat(aTabData);
+        aSelectTab -= firstVisibleTab;
+      }
+    }
+
+    // make sure to restore the selected tab first (if any)
+    if (aSelectTab-- && aTabs[aSelectTab]) {
+      aTabs.unshift(aTabs.splice(aSelectTab, 1)[0]);
+      aTabData.unshift(aTabData.splice(aSelectTab, 1)[0]);
+      tabbrowser.selectedTab = aTabs[0];
+    }
+
+    // Prepare the tabs so that they can be properly restored. We'll pin/unpin
+    // and show/hide tabs as necessary. We'll also set the labels, user typed
+    // value, and attach a copy of the tab's data in case we close it before
+    // it's been restored.
+    for (t = 0; t < aTabs.length; t++) {
+      let tab = aTabs[t];
+      let browser = tabbrowser.getBrowserForTab(tab);
+      let tabData = aTabData[t];
+
+      if (tabData.hidden) {
+        tab.setAttribute("hidden", true);
+      } else {
+        if (tab.hidden) {
+          tab.removeAttribute("hidden");
+        }
+      }
+
+      for (let name in tabData.attributes)
+        this.xulAttributes[name] = true;
+
+      // keep the data around to prevent dataloss in case
+      // a tab gets closed before it's been properly restored
+      browser.__SS_data = tabData;
+      browser.__SS_restoreState = TAB_STATE_NEEDS_RESTORE;
+
+      // Make sure that set/getTabValue will set/read the correct data by
+      // wiping out any current value in tab.__SS_extdata.
+      delete tab.__SS_extdata;
+
+      if (!tabData.entries || tabData.entries.length == 0) {
+        // make sure to blank out this tab's content
+        // (just purging the tab's history won't be enough)
+        browser.contentDocument.location = "about:blank";
+        continue;
+      }
+
+      browser.stop(); // in case about:blank isn't done yet
+
+      // wall-paper fix for bug 439675: make sure that the URL to be loaded
+      // is always visible in the address bar
+      let activeIndex = (tabData.index || tabData.entries.length) - 1;
+      let activePageData = tabData.entries[activeIndex] || null;
+      let uri = activePageData ? activePageData.url || null : null;
+
+      // NB: we won't set initial URIs (about:blank, about:privatebrowsing, etc.)
+      // here because their load will not normally trigger a location bar clearing
+      // when they finish loading (to avoid race conditions where we then
+      // clear user input instead), so we shouldn't set them here either.
+      // They also don't fall under the issues in bug 439675 where user input
+      // needs to be preserved if the load doesn't succeed.
+      if (!browser.userTypedValue && uri && !aWindow.gInitialPages.has(uri)) {
+        browser.userTypedValue = uri;
+      }
+
+      // Also make sure currentURI is set so that switch-to-tab works before
+      // the tab is restored. We'll reset this to about:blank when we try to
+      // restore the tab to ensure that docshell doeesn't get confused.
+      if (uri)
+        browser.docShell.setCurrentURI(this._getURIFromString(uri));
+
+      // If the page has a title, set it.
+      if (activePageData) {
+        if (activePageData.title) {
+          tab.label = activePageData.title;
+          tab.crop = "end";
+        } else if (activePageData.url != "about:blank") {
+          tab.label = activePageData.url;
+          tab.crop = "center";
+        }
+      }
+    }
+
+    // helper hashes for ensuring unique frame IDs and unique document
+    // identifiers.
+    var idMap = { used: {} };
+    var docIdentMap = {};
+    this.restoreHistory(aWindow, aTabs, aTabData, idMap, docIdentMap);
+  },
+
+  /**
+   * Restore history for a window
+   * @param aWindow
+   *        Window reference
+   * @param aTabs
+   *        Array of tab references
+   * @param aTabData
+   *        Array of tab data
+   * @param aIdMap
+   *        Hash for ensuring unique frame IDs
+   */
+  restoreHistory:
+    function sss_restoreHistory(aWindow, aTabs, aTabData, aIdMap, aDocIdentMap) {
+    // if the tab got removed before being completely restored, then skip it
+    while (aTabs.length > 0 && (!aTabs[0].parentNode || !aTabs[0].linkedBrowser)) {
+      aTabs.shift();
+      aTabData.shift();
+    }
+    if (aTabs.length == 0) {
+      // At this point we're essentially ready for consumers to read/write data
+      // via the sessionstore API so we'll send the SSWindowStateReady event.
+      this._sendWindowStateEvent(aWindow, "Ready");
+      return; // no more tabs to restore
+    }
+
+    var tab = aTabs.shift();
+    var tabData = aTabData.shift();
+
+    var browser = aWindow.getBrowser().getBrowserForTab(tab);
+    var history = browser.webNavigation.sessionHistory;
+
+    if (history.count > 0) {
+      history.PurgeHistory(history.count);
+    }
+
+    browser.__SS_shistoryListener = new SessionStoreSHistoryListener(this, tab);
+    history.addSHistoryListener(browser.__SS_shistoryListener);
+
+    if (!tabData.entries) {
+      tabData.entries = [];
+    }
+    if (tabData.extData) {
+      tab.__SS_extdata = {};
+      for (let key in tabData.extData)
+        tab.__SS_extdata[key] = tabData.extData[key];
+    }
+    else
+      delete tab.__SS_extdata;
+
+    for (var i = 0; i < tabData.entries.length; i++) {
+      let cloneEntry = false;
+      //XXXzpao Wallpaper patch for bug 509315
+      if (!tabData.entries[i].url)
+        continue;
+
+      let shEntry = this._deserializeHistoryEntry(tabData.entries[i],
+                                                  aIdMap, aDocIdentMap);
+      try {
+        history.addEntry(shEntry, true);
+      }
+      catch (ex) {
+        cloneEntry = true;
+      }
+
+      // Workaround for bug 1466911.
+      // FIXME Remove this after the issue which caused the exception above
+      // to be thrown has been fixed.
+      if (cloneEntry) {
+        shEntry = shEntry.clone();
+        shEntry.abandonBFCacheEntry();
+
+        try {
+          history.addEntry(shEntry, true);
+        }
+        catch (ex) {
+          Cu.reportError(ex);
+        }
+      }
+    }
+
+    // make sure to reset the capabilities and attributes, in case this tab gets reused
+    var disallow = (tabData.disallow)?tabData.disallow.split(","):[];
+    CAPABILITIES.forEach(function(aCapability) {
+      browser.docShell["allow" + aCapability] = !disallow.includes(aCapability);
+    });
+    for (let name in this.xulAttributes)
+      tab.removeAttribute(name);
+    for (let name in tabData.attributes)
+      tab.setAttribute(name, tabData.attributes[name]);
+
+    if (tabData.storage && browser.docShell instanceof Ci.nsIDocShell)
+      this._deserializeSessionStorage(tabData.storage, browser.docShell);
+
+    // notify the tabbrowser that the tab chrome has been restored
+    var event = aWindow.document.createEvent("Events");
+    event.initEvent("SSTabRestoring", true, false);
+    tab.dispatchEvent(event);
+
+    // Restore the history in the next tab
+    Services.tm.mainThread.dispatch(this.restoreHistory.bind(this, aWindow,
+      aTabs, aTabData, aIdMap, aDocIdentMap), Ci.nsIThread.DISPATCH_NORMAL);
+
+    // This could cause us to ignore the max_concurrent_tabs pref a bit, but
+    // it ensures each window will have its selected tab loaded.
+    if (aWindow.getBrowser().selectedBrowser == browser) {
+      this.restoreTab(tab);
+    }
+    else {
+      // Put the tab into the right bucket
+      if (tabData.hidden)
+        this._tabsToRestore.hidden.push(tab);
+      else
+        this._tabsToRestore.visible.push(tab);
+      this.restoreNextTab();
+    }
+  },
+
+  /**
+   * Restores the specified tab. If the tab can't be restored (eg, no history or
+   * calling gotoIndex fails), then state changes will be rolled back.
+   * This method will check if gTabsProgressListener is attached to the tab's
+   * window, ensuring that we don't get caught without one.
+   * This method removes the session history listener right before starting to
+   * attempt a load. This will prevent cases of "stuck" listeners.
+   * If this method returns false, then it is up to the caller to decide what to
+   * do. In the common case (restoreNextTab), we will want to then attempt to
+   * restore the next tab. In the other case (selecting the tab, reloading the
+   * tab), the caller doesn't actually want to do anything if no page is loaded.
+   *
+   * @param aTab
+   *        the tab to restore
+   *
+   * @returns true/false indicating whether or not a load actually happened
+   */
+  restoreTab: function sss_restoreTab(aTab) {
+    let window = aTab.ownerDocument.defaultView;
+    let browser = aTab.linkedBrowser;
+    let tabData = browser.__SS_data;
+
+    // If the tabData which we're sending down has any sessionStorage associated
+    // with it, we need to send down permissions for the domains, as this
+    // information will be needed to correctly restore the session.
+    if (tabData.storage) {
+      for (let origin of Object.getOwnPropertyNames(tabData.storage)) {
+        try {
+          let {frameLoader} = browser;
+          if (frameLoader.tabParent) {
+            let attrs = browser.contentPrincipal.originAttributes;
+            let dataPrincipal = Services.scriptSecurityManager.createCodebasePrincipalFromOrigin(origin);
+            let principal = Services.scriptSecurityManager.createCodebasePrincipal(dataPrincipal.URI, attrs);
+            frameLoader.tabParent.transmitPermissionsForPrincipal(principal);
+          }
+        } catch (e) {
+          Cu.reportError(e);
+        }
+      }
+    }
+
+    // There are cases within where we haven't actually started a load. In that
+    // that case we'll reset state changes we made and return false to the caller
+    // can handle appropriately.
+    let didStartLoad = false;
+
+    // Make sure that the tabs progress listener is attached to this window
+    this._ensureTabsProgressListener(window);
+
+    // Make sure that this tab is removed from _tabsToRestore
+    this._removeTabFromTabsToRestore(aTab);
+
+    // Increase our internal count.
+    this._tabsRestoringCount++;
+
+    // Set this tab's state to restoring
+    browser.__SS_restoreState = TAB_STATE_RESTORING;
+
+    // Remove the history listener, since we no longer need it once we start restoring
+    this._removeSHistoryListener(aTab);
+
+    let activeIndex = (tabData.index || tabData.entries.length) - 1;
+    if (activeIndex >= tabData.entries.length)
+      activeIndex = tabData.entries.length - 1;
+
+    // Reset currentURI.
+    browser.webNavigation.setCurrentURI(this._getURIFromString("about:blank"));
+
+    // Attach data that will be restored on "load" event, after tab is restored.
+    if (activeIndex > -1) {
+      // restore those aspects of the currently active documents which are not
+      // preserved in the plain history entries (mainly scroll state and text data)
+      browser.__SS_restore_data = tabData.entries[activeIndex] || {};
+      browser.__SS_restore_pageStyle = tabData.pageStyle || "";
+      browser.__SS_restore_tab = aTab;
+
+      didStartLoad = true;
+      try {
+        // In order to work around certain issues in session history, we need to
+        // force session history to update its internal index and call reload
+        // instead of gotoIndex. See bug 597315.
+        var sessionHistory = browser.webNavigation.sessionHistory;
+        sessionHistory.index = activeIndex;
+        sessionHistory.reloadCurrentEntry();
+      }
+      catch (ex) {
+        // ignore page load errors
+        aTab.removeAttribute("busy");
+        didStartLoad = false;
+      }
+    }
+
+    // Handle userTypedValue. Setting userTypedValue seems to update gURLbar
+    // as needed. Calling loadURI will cancel form filling in restoreDocument
+    if (tabData.userTypedValue) {
+      browser.userTypedValue = tabData.userTypedValue;
+
+      if (tabData.userTypedClear) {
+        // Make it so that we'll enter restoreDocument on page load. We will
+        // fire SSTabRestored from there. We don't have any form data to
+        // restore so we can just set the URL to null.
+        browser.__SS_restore_data = { url: null };
+        browser.__SS_restore_tab = aTab;
+        didStartLoad = true;
+        browser.webNavigation
+               .loadURI(tabData.userTypedValue,
+                        Ci.nsIWebNavigation.LOAD_FLAGS_ALLOW_THIRD_PARTY_FIXUP,
+                        null, null, null,
+                        Services.scriptSecurityManager.getSystemPrincipal());
+      }
+    }
+
+    // If we didn't start a load, then we won't reset this tab through the usual
+    // channel (via the progress listener), so reset the tab ourselves. We will
+    // also send SSTabRestored since this tab has technically been restored.
+    if (!didStartLoad) {
+      this._sendTabRestoredNotification(aTab);
+      this._resetTabRestoringState(aTab);
+    }
+
+    return didStartLoad;
+  },
+
+  /**
+   * This _attempts_ to restore the next available tab. If the restore fails,
+   * then we will attempt the next one.
+   * There are conditions where this won't do anything:
+   *   if we're in the process of quitting
+   *   if there are no tabs to restore
+   *   if we have already reached the limit for number of tabs to restore
+   */
+  restoreNextTab: function sss_restoreNextTab() {
+    // If we call in here while quitting, we don't actually want to do anything
+    if (this._loadState == STATE_QUITTING)
+      return;
+
+    // If it's not possible to restore anything, then just bail out.
+    if (this._maxConcurrentTabRestores >= 0 &&
+        this._tabsRestoringCount >= this._maxConcurrentTabRestores)
+      return;
+
+    // Look in visible, then hidden
+    let nextTabArray;
+    if (this._tabsToRestore.visible.length) {
+      nextTabArray = this._tabsToRestore.visible;
+    }
+    else if (this._tabsToRestore.hidden.length) {
+      nextTabArray = this._tabsToRestore.hidden;
+    }
+
+    if (nextTabArray) {
+      let tab = nextTabArray.shift();
+      let didStartLoad = this.restoreTab(tab);
+      // If we don't start a load in the restored tab (eg, no entries) then we
+      // want to attempt to restore the next tab.
+      if (!didStartLoad)
+        this.restoreNextTab();
+    }
+  },
+
+  /**
+   * expands serialized history data into a session-history-entry instance
+   * @param aEntry
+   *        Object containing serialized history data for a URL
+   * @param aIdMap
+   *        Hash for ensuring unique frame IDs
+   * @returns nsISHEntry
+   */
+  _deserializeHistoryEntry:
+    function sss_deserializeHistoryEntry(aEntry, aIdMap, aDocIdentMap) {
+
+    var shEntry = Cc["@mozilla.org/browser/session-history-entry;1"]
+                    .createInstance(Ci.nsISHEntry);
+
+    shEntry.URI = this._getURIFromString(aEntry.url);
+    shEntry.title = aEntry.title || aEntry.url;
+    if (aEntry.subframe)
+      shEntry.isSubFrame = aEntry.subframe || false;
+    shEntry.loadType = Ci.nsIDocShellLoadInfo.loadHistory;
+    if (aEntry.contentType)
+      shEntry.contentType = aEntry.contentType;
+    if (aEntry.referrer)
+      shEntry.referrerURI = this._getURIFromString(aEntry.referrer);
+
+    if (aEntry.cacheKey) {
+      var cacheKey = Cc["@mozilla.org/supports-PRUint32;1"]
+                       .createInstance(Ci.nsISupportsPRUint32);
+      cacheKey.data = aEntry.cacheKey;
+      shEntry.cacheKey = cacheKey;
+    }
+
+    if (aEntry.ID) {
+      // get a new unique ID for this frame (since the one from the last
+      // start might already be in use)
+      var id = aIdMap[aEntry.ID] || 0;
+      if (!id) {
+        for (id = Date.now(); id in aIdMap.used; id++);
+        aIdMap[aEntry.ID] = id;
+        aIdMap.used[id] = true;
+      }
+      shEntry.ID = id;
+    }
+
+    // If we have the legacy docshellID on our entry, upgrade it to a
+    // docshellUUID by going through the mapping.
+    if (aEntry.docshellID) {
+      if (!this._docshellUUIDMap.has(aEntry.docshellID)) {
+        // Convert the nsID to a string so that the docshellUUID property
+        // is correctly stored as a string.
+        this._docshellUUIDMap.set(aEntry.docshellID,
+                                  uuidGenerator.generateUUID().toString());
+      }
+      aEntry.docshellUUID = this._docshellUUIDMap.get(aEntry.docshellID);
+      delete aEntry.docshellID;
+    }
+
+    if (aEntry.docshellUUID)
+      shEntry.docshellID = Components.ID(aEntry.docshellUUID);
+
+    if (aEntry.structuredCloneState && aEntry.structuredCloneVersion) {
+      shEntry.stateData =
+        Cc["@mozilla.org/docshell/structured-clone-container;1"]
+          .createInstance(Ci.nsIStructuredCloneContainer);
+
+      shEntry.stateData.initFromBase64(aEntry.structuredCloneState,
+                                       aEntry.structuredCloneVersion);
+    }
+
+    if (aEntry.scroll) {
+      var scrollPos = (aEntry.scroll || "0,0").split(",");
+      scrollPos = [parseInt(scrollPos[0]) || 0, parseInt(scrollPos[1]) || 0];
+      shEntry.setScrollPosition(scrollPos[0], scrollPos[1]);
+    }
+
+    if (aEntry.postdata_b64) {
+      var postdata = atob(aEntry.postdata_b64);
+      var stream = Cc["@mozilla.org/io/string-input-stream;1"]
+                     .createInstance(Ci.nsIStringInputStream);
+      stream.setData(postdata, postdata.length);
+      shEntry.postData = stream;
+    }
+
+    let childDocIdents = {};
+    if (aEntry.docIdentifier) {
+      // If we have a serialized document identifier, try to find an SHEntry
+      // which matches that doc identifier and adopt that SHEntry's
+      // BFCacheEntry.  If we don't find a match, insert shEntry as the match
+      // for the document identifier.
+      let matchingEntry = aDocIdentMap[aEntry.docIdentifier];
+      if (!matchingEntry) {
+        matchingEntry = {shEntry: shEntry, childDocIdents: childDocIdents};
+        aDocIdentMap[aEntry.docIdentifier] = matchingEntry;
+      }
+      else {
+        shEntry.adoptBFCacheEntry(matchingEntry.shEntry);
+        childDocIdents = matchingEntry.childDocIdents;
+      }
+    }
+
+    // The field entry.owner_b64 got renamed to entry.triggeringPricipal_b64 in
+    // Bug 1286472 and Bug 1334780 for SeaMonkey.
+    // To remain backward compatible we still have to support that field for a
+    // few cycles before we can remove it.
+    if (aEntry.owner_b64) {
+      aEntry.triggeringPricipal_b64 = aEntry.owner_b64;
+      delete aEntry.owner_b64;
+    }
+
+    // Before introducing the concept of principalToInherit we only had
+    // a triggeringPrincipal within every entry which basically is the
+    // equivalent of the new principalToInherit. To avoid compatibility
+    // issues, we first check if the entry has entries for
+    // triggeringPrincipal_base64 and principalToInherit_base64. If not
+    // we fall back to using the principalToInherit (which is stored
+    // as triggeringPrincipal_b64) as the triggeringPrincipal and
+    // the principalToInherit.
+    // FF55 will remove the triggeringPrincipal_b64, see Bug 1301666.
+    if (aEntry.triggeringPrincipal_base64 || aEntry.principalToInherit_base64) {
+      if (aEntry.triggeringPrincipal_base64) {
+        shEntry.triggeringPrincipal =
+          Utils.deserializePrincipal(aEntry.triggeringPrincipal_base64);
+      }
+      if (aEntry.principalToInherit_base64) {
+        shEntry.principalToInherit =
+          Utils.deserializePrincipal(aEntry.principalToInherit_base64);
+      }
+    } else if (aEntry.triggeringPrincipal_b64) {
+      shEntry.triggeringPrincipal = Utils.deserializePrincipal(aEntry.triggeringPrincipal_b64);
+      shEntry.principalToInherit = shEntry.triggeringPrincipal;
+    }
+
+    if (aEntry.children && shEntry instanceof Ci.nsISHContainer) {
+      for (var i = 0; i < aEntry.children.length; i++) {
+        //XXXzpao Wallpaper patch for bug 509315
+        if (!aEntry.children[i].url)
+          continue;
+
+        // We're mysteriously getting sessionrestore.js files with a cycle in
+        // the doc-identifier graph.  (That is, we have an entry where doc
+        // identifier A is an ancestor of doc identifier B, and another entry
+        // where doc identifier B is an ancestor of A.)
+        //
+        // If we were to respect these doc identifiers, we'd create a cycle in
+        // the SHEntries themselves, which causes the docshell to loop forever
+        // when it looks for the root SHEntry.
+        //
+        // So as a hack to fix this, we restrict the scope of a doc identifier
+        // to be a node's siblings and cousins, and pass childDocIdents, not
+        // aDocIdents, to _deserializeHistoryEntry.  That is, we say that two
+        // SHEntries with the same doc identifier have the same document iff
+        // they have the same parent or their parents have the same document.
+
+        shEntry.AddChild(this._deserializeHistoryEntry(aEntry.children[i], aIdMap,
+                                                       childDocIdents), i);
+      }
+    }
+
+    return shEntry;
+  },
+
+  /**
+   * restores all sessionStorage "super cookies"
+   * @param aStorageData
+   *        Storage data to be restored
+   * @param aDocShell
+   *        A tab's docshell (containing the sessionStorage)
+   */
+  _deserializeSessionStorage: function sss_deserializeSessionStorage(aStorageData, aDocShell) {
+
+    for (let origin of Object.keys(aStorageData)) {
+      let data = aStorageData[origin];
+
+      let principal;
+
+      try {
+        // NOTE: We record the full origin for the URI which the
+        // sessionStorage is being captured for. As of bug 1319114 this code
+        // stopped parsing any origins which have originattributes correctly, as
+        // it decided to use the origin attributes from the docshell, and try to
+        // interpret the origin as a URI. Since bug 1473426 code now correctly
+        // parses the full origin, and then discards the origin attributes, to
+        // make the behavior line up with the original intentions in bug 1235657
+        // while preserving the ability to read all session storage from
+        // previous versions. In the future, if this behavior is desired, we may
+        // want to use the spec instead of the origin as the key, and avoid
+        // transmitting origin attribute information which we then discard when
+        // restoring.
+        //
+        // If changing this logic, make sure to also change the principal
+        // computation logic in restoretab.
+        let attrs = aDocShell.getOriginAttributes();
+        let dataPrincipal = Services.scriptSecurityManager.createCodebasePrincipalFromOrigin(origin);
+        principal = Services.scriptSecurityManager.createCodebasePrincipal(dataPrincipal.URI, attrs);
+      } catch (e) {
+        Cu.reportError(e);
+        continue;
+      }
+
+      let storageManager = aDocShell.QueryInterface(Ci.nsIDOMStorageManager);
+      let window = aDocShell.QueryInterface(Ci.nsIInterfaceRequestor)
+                            .getInterface(Ci.nsIDOMWindow);
+
+      // There is no need to pass documentURI, it's only used to fill documentURI property of
+      // domstorage event, which in this case has no consumer. Prevention of events in case
+      // of missing documentURI will be solved in a followup bug to bug 600307.
+      let storage = storageManager.createStorage(window, principal, "");
+
+      for (let key of Object.keys(data)) {
+        try {
+          storage.setItem(key, data[key]);
+        } catch (e) {
+          // Throws e.g. for URIs that can't have sessionStorage.
+          Cu.reportError(e);
+        }
+      }
+    }
+  },
+
+  /**
+   * Restore properties to a loaded document
+   */
+  restoreDocument: function sss_restoreDocument(aWindow, aBrowser, aEvent) {
+    // wait for the top frame to be loaded completely
+    if (!aEvent || !aEvent.originalTarget || !aEvent.originalTarget.defaultView || aEvent.originalTarget.defaultView != aEvent.originalTarget.defaultView.top) {
+      return;
+    }
+
+    // always call this before injecting content into a document!
+    function hasExpectedURL(aDocument, aURL) {
+      return !aURL || aURL.replace(/#.*/, "") == aDocument.location.href.replace(/#.*/, "");
+    }
+
+    function restoreFormData(aDocument, aData, aURL) {
+      for (let key in aData) {
+        if (!hasExpectedURL(aDocument, aURL))
+          return;
+
+        let node = key.charAt(0) == "#" ? aDocument.getElementById(key.slice(1)) :
+                                          XPathGenerator.resolve(aDocument, key);
+        if (!node)
+          continue;
+
+        let eventType;
+        let value = aData[key];
+        if (typeof value == "string" && node.type != "file") {
+          if (node.value == value)
+            continue; // don't dispatch an input event for no change
+
+          node.value = value;
+          eventType = "input";
+        }
+        else if (typeof value == "boolean") {
+          if (node.checked == value)
+            continue; // don't dispatch a change event for no change
+
+          node.checked = value;
+          eventType = "change";
+        }
+        else if (typeof value == "number") {
+          // We saved the value blindly since selects take more work to determine
+          // default values. So now we should check to avoid unnecessary events.
+          if (node.selectedIndex == value)
+            continue;
+
+          try {
+            node.selectedIndex = value;
+            eventType = "change";
+          } catch (ex) { /* throws for invalid indices */ }
+        }
+        else if (value && value.fileList && value.type == "file" && node.type == "file") {
+          node.mozSetFileNameArray(value.fileList, value.fileList.length);
+          eventType = "input";
+        }
+        else if (value && typeof value.indexOf == "function" && node.options) {
+          Array.from(node.options).forEach(function(aOpt, aIx) {
+            aOpt.selected = value.includes(aIx);
+
+            // Only fire the event here if this wasn't selected by default
+            if (!aOpt.defaultSelected)
+              eventType = "change";
+          });
+        }
+
+        // Fire events for this node if applicable
+        if (eventType) {
+          let event = aDocument.createEvent("UIEvents");
+          event.initUIEvent(eventType, true, true, aDocument.defaultView, 0);
+          node.dispatchEvent(event);
+        }
+      }
+    }
+
+    let selectedPageStyle = aBrowser.__SS_restore_pageStyle;
+    function restoreTextDataAndScrolling(aContent, aData, aPrefix) {
+      if (aData.formdata)
+        restoreFormData(aContent.document, aData.formdata, aData.url);
+      if (aData.innerHTML) {
+        aWindow.setTimeout(function() {
+          if (aContent.document.designMode == "on" &&
+              hasExpectedURL(aContent.document, aData.url)) {
+            aContent.document.body.innerHTML = aData.innerHTML;
+          }
+        }, 0);
+      }
+      var match;
+      if (aData.scroll && (match = /(\d+),(\d+)/.exec(aData.scroll)) != null) {
+        aContent.scrollTo(match[1], match[2]);
+      }
+      Array.from(aContent.document.styleSheets).forEach(function(aSS) {
+        aSS.disabled = aSS.title && aSS.title != selectedPageStyle;
+      });
+      for (var i = 0; i < aContent.frames.length; i++) {
+        if (aData.children && aData.children[i] &&
+          hasExpectedURL(aContent.document, aData.url)) {
+          restoreTextDataAndScrolling(aContent.frames[i], aData.children[i], aPrefix + i + "|");
+        }
+      }
+    }
+
+    // don't restore text data and scrolling state if the user has navigated
+    // away before the loading completed (except for in-page navigation)
+    if (hasExpectedURL(aEvent.originalTarget, aBrowser.__SS_restore_data.url)) {
+      var content = aEvent.originalTarget.defaultView;
+      restoreTextDataAndScrolling(content, aBrowser.__SS_restore_data, "");
+      aBrowser.markupDocumentViewer.authorStyleDisabled = selectedPageStyle == "_nostyle";
+    }
+
+    // notify the tabbrowser that this document has been completely restored
+    this._sendTabRestoredNotification(aBrowser.__SS_restore_tab);
+
+    delete aBrowser.__SS_restore_data;
+    delete aBrowser.__SS_restore_pageStyle;
+    delete aBrowser.__SS_restore_tab;
+  },
+
+  /**
+   * Restore visibility and dimension features to a window
+   * @param aWindow
+   *        Window reference
+   * @param aWinData
+   *        Object containing session data for the window
+   */
+  restoreWindowFeatures: function sss_restoreWindowFeatures(aWindow, aWinData) {
+    var hidden = (aWinData.hidden)?aWinData.hidden.split(","):[];
+    WINDOW_HIDEABLE_FEATURES.forEach(function(aItem) {
+      aWindow[aItem].visible = !hidden.includes(aItem);
+    });
+
+    if (aWinData.isPopup)
+      this._windows[aWindow.__SSi].isPopup = true;
+    else
+      delete this._windows[aWindow.__SSi].isPopup;
+
+    Services.tm.mainThread.dispatch(this.restoreDimensions.bind(this, aWindow,
+        +aWinData.width || 0,
+        +aWinData.height || 0,
+        "screenX" in aWinData ? +aWinData.screenX : NaN,
+        "screenY" in aWinData ? +aWinData.screenY : NaN,
+        aWinData.sizemode || "", aWinData.sidebar || ""),
+      Ci.nsIThread.DISPATCH_NORMAL);
+  },
+
+  /**
+   * Restore a window's dimensions
+   * @param aWidth
+   *        Window width
+   * @param aHeight
+   *        Window height
+   * @param aLeft
+   *        Window left
+   * @param aTop
+   *        Window top
+   * @param aSizeMode
+   *        Window size mode (eg: maximized)
+   * @param aSidebar
+   *        Sidebar command
+   */
+  restoreDimensions: function sss_restoreDimensions(aWindow, aWidth, aHeight, aLeft, aTop, aSizeMode, aSidebar) {
+    var win_ = this._getWindowDimension.bind(this, aWindow);
+
+    // find available space on the screen where this window is being placed
+    let screen = gScreenManager.screenForRect(aLeft, aTop, aWidth, aHeight);
+    if (screen) {
+      let screenLeft = {}, screenTop = {}, screenWidth = {}, screenHeight = {};
+      screen.GetAvailRectDisplayPix(screenLeft, screenTop, screenWidth, screenHeight);
+      // constrain the dimensions to the actual space available
+      if (aWidth > screenWidth.value) {
+        aWidth = screenWidth.value;
+      }
+      if (aHeight > screenHeight.value) {
+        aHeight = screenHeight.value;
+      }
+      // and then pull the window within the screen's bounds
+      if (aLeft < screenLeft.value) {
+        aLeft = screenLeft.value;
+      } else if (aLeft + aWidth > screenLeft.value + screenWidth.value) {
+        aLeft = screenLeft.value + screenWidth.value - aWidth;
+      }
+      if (aTop < screenTop.value) {
+        aTop = screenTop.value;
+      } else if (aTop + aHeight > screenTop.value + screenHeight.value) {
+        aTop = screenTop.value + screenHeight.value - aHeight;
+      }
+    }
+
+    // only modify those aspects which aren't correct yet
+    if (aWidth && aHeight && (aWidth != win_("width") || aHeight != win_("height"))) {
+      aWindow.resizeTo(aWidth, aHeight);
+    }
+    if (!isNaN(aLeft) && !isNaN(aTop) && (aLeft != win_("screenX") || aTop != win_("screenY"))) {
+      aWindow.moveTo(aLeft, aTop);
+    }
+    if (aSizeMode && win_("sizemode") != aSizeMode)
+    {
+      switch (aSizeMode)
+      {
+      case "maximized":
+        aWindow.maximize();
+        break;
+      case "minimized":
+        aWindow.minimize();
+        break;
+      case "normal":
+        aWindow.restore();
+        break;
+      }
+    }
+    var sidebar = aWindow.document.getElementById("sidebar-box");
+    if (sidebar.getAttribute("sidebarcommand") != aSidebar) {
+      aWindow.toggleSidebar(aSidebar);
+    }
+    // since resizing/moving a window brings it to the foreground,
+    // we might want to re-focus the last focused window
+    if (this.windowToFocus && this.windowToFocus.content) {
+      this.windowToFocus.content.focus();
+    }
+  },
+
+  /**
+   * Restores cookies
+   * @param aCookies
+   *        Array of cookie objects
+   */
+  restoreCookies: function sss_restoreCookies(aCookies) {
+    // MAX_EXPIRY should be 2^63-1, but JavaScript can't handle that precision
+    var MAX_EXPIRY = Math.pow(2, 62);
+    for (let i = 0; i < aCookies.length; i++) {
+      var cookie = aCookies[i];
+      try {
+        Services.cookies.add(cookie.host, cookie.path || "", cookie.name || "",
+                             cookie.value, !!cookie.secure, !!cookie.httponly,
+                             true,
+                             "expiry" in cookie ? cookie.expiry : MAX_EXPIRY,
+                             "originAttributes" in cookie ? cookie.originAttributes : {});
+      }
+      catch (ex) { Cu.reportError(ex); } // don't let a single cookie stop recovering
+    }
+  },
+
+/* ........ Disk Access .............. */
+
+  /**
+   * save state delayed by N ms
+   * marks window as dirty (i.e. data update can't be skipped)
+   * @param aWindow
+   *        Window reference
+   * @param aDelay
+   *        Milliseconds to delay
+   */
+  saveStateDelayed: function sss_saveStateDelayed(aWindow, aDelay) {
+    if (aWindow) {
+      DirtyWindows.add(aWindow);
+    }
+
+    if (!this._saveTimer && this._resume_from_crash) {
+      // interval until the next disk operation is allowed
+      var minimalDelay = this._lastSaveTime + this._interval - Date.now();
+
+      // if we have to wait, set a timer, otherwise saveState directly
+      aDelay = Math.max(minimalDelay, aDelay || 2000);
+      if (aDelay > 0) {
+        this._saveTimer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+        this._saveTimer.init(this, aDelay, Ci.nsITimer.TYPE_ONE_SHOT);
+      }
+      else {
+        this.saveState();
+      }
+    }
+  },
+
+  /**
+   * save state to disk
+   * @param aUpdateAll
+   *        Bool update all windows
+   */
+  saveState: function sss_saveState(aUpdateAll) {
+    // if crash recovery is disabled, only save session resuming information
+    if (!this._resume_from_crash && this._loadState == STATE_RUNNING)
+      return;
+
+    // If crash recovery is disabled, we only want to resume with pinned tabs
+    // if we crash.
+    let pinnedOnly = this._loadState == STATE_RUNNING && !this._resume_from_crash;
+
+    var oState = this._getCurrentState(aUpdateAll);
+    if (!oState)
+      return;
+
+    // Persist the last session if we deferred restoring it
+    if (this._lastSessionState)
+      oState.lastSessionState = this._lastSessionState;
+
+    this._saveStateObject(oState);
+  },
+
+  /**
+   * write a state object to disk
+   */
+  _saveStateObject: function sss_saveStateObject(aStateObj) {
+    var stateString = Cc["@mozilla.org/supports-string;1"]
+                        .createInstance(Ci.nsISupportsString);
+    // parentheses are for backwards compatibility with older sessionstore files
+    stateString.data = this._toJSONString(aStateObj);
+
+    Services.obs.notifyObservers(stateString, "sessionstore-state-write");
+
+    // don't touch the file if an observer has deleted all state data
+    if (stateString.data)
+      this._writeFile(this._sessionFile, stateString.data);
+
+    this._lastSaveTime = Date.now();
+  },
+
+  /**
+   * delete session datafile and backup
+   */
+  _clearDisk: function sss_clearDisk() {
+    if (this._sessionFile.exists()) {
+      try {
+        this._sessionFile.remove(false);
+      }
+      catch (ex) { dump(ex + '\n'); } // couldn't remove the file - what now?
+    }
+    if (this._sessionFileBackup.exists()) {
+      try {
+        this._sessionFileBackup.remove(false);
+      }
+      catch (ex) { dump(ex + '\n'); } // couldn't remove the file - what now?
+    }
+  },
+
+/* ........ Auxiliary Functions .............. */
+
+  /**
+   * call a callback for all currently opened browser windows
+   * (might miss the most recent one)
+   * @param aFunc
+   *        Callback each window is passed to
+   */
+  _forEachBrowserWindow: function sss_forEachBrowserWindow(aFunc) {
+    var windowsEnum = Services.wm.getEnumerator("navigator:browser");
+
+    while (windowsEnum.hasMoreElements()) {
+      var window = windowsEnum.getNext();
+      if (!window.closed && window.__SSi) {
+        aFunc.call(this, window);
+      }
+    }
+  },
+
+  /**
+   * Returns most recent window
+   * @returns Window reference
+   */
+  _getMostRecentBrowserWindow: function sss_getMostRecentBrowserWindow() {
+    var win = Services.wm.getMostRecentWindow("navigator:browser");
+    if (!win)
+      return null;
+    if (!win.closed)
+      return win;
+
+    let broken_wm_z_order =
+      AppConstants.platform != "macosx" && AppConstants.platform != "win";
+
+    if (broken_wm_z_order) {
+      win = null;
+      var windowsEnum = Services.wm.getEnumerator("navigator:browser");
+      // this is oldest to newest, so this gets a bit ugly
+      while (windowsEnum.hasMoreElements()) {
+        let nextWin = windowsEnum.getNext();
+        if (!nextWin.closed)
+          win = nextWin;
+      }
+      return win;
+    }
+
+    var windowsEnum =
+      Services.wm.getZOrderDOMWindowEnumerator("navigator:browser", true);
+
+    while (windowsEnum.hasMoreElements()) {
+      win = windowsEnum.getNext();
+      if (!win.closed)
+        return win;
+    }
+
+    return null;
+  },
+
+  /**
+   * Calls onClose for windows that are determined to be closed but aren't
+   * destroyed yet, which would otherwise cause getBrowserState and
+   * setBrowserState to treat them as open windows.
+   */
+  _handleClosedWindows: function sss_handleClosedWindows() {
+    var windowsEnum = Services.wm.getEnumerator("navigator:browser");
+
+    while (windowsEnum.hasMoreElements()) {
+      var window = windowsEnum.getNext();
+      if (window.closed) {
+        this.onClose(window);
+      }
+    }
+  },
+
+  /**
+   * open a new browser window for a given session state
+   * called when restoring a multi-window session
+   * @param aState
+   *        Object containing session data
+   */
+  _openWindowWithState: function sss_openWindowWithState(aState) {
+    var argString = Cc["@mozilla.org/supports-string;1"]
+                      .createInstance(Ci.nsISupportsString);
+    argString.data = "about:blank";
+
+    var features = "chrome,dialog=no,suppressanimation,all";
+    var winState = aState.windows[0];
+    for (var aAttr in WINDOW_ATTRIBUTES) {
+      // Use !isNaN as an easy way to ignore sizemode and check for numbers
+      if (aAttr in winState && !isNaN(winState[aAttr]))
+        features += "," + WINDOW_ATTRIBUTES[aAttr] + "=" + winState[aAttr];
+    }
+
+    var window =
+      Services.ww.openWindow(null, this._prefBranch.getCharPref("chromeURL"),
+                             "_blank", features, argString);
+
+    do {
+      var ID = "window" + Math.random();
+    } while (ID in this._statesToRestore);
+    this._statesToRestore[(window.__SS_restoreID = ID)] = aState;
+
+    return window;
+  },
+
+  /**
+   * Gets the tab for the given browser. This should be marginally better
+   * than using tabbrowser's getTabForContentWindow. This assumes the browser
+   * is the linkedBrowser of a tab, not a dangling browser.
+   *
+   * @param aBrowser
+   *        The browser from which to get the tab.
+   */
+  _getTabForBrowser: function sss_getTabForBrowser(aBrowser) {
+    let windowTabs = aBrowser.ownerDocument.defaultView.getBrowser().tabs;
+    for (let i = 0; i < windowTabs.length; i++) {
+      let tab = windowTabs[i];
+      if (tab.linkedBrowser == aBrowser)
+        return tab;
+    }
+  },
+
+  /**
+   * Whether or not to resume session, if not recovering from a crash.
+   * @returns bool
+   */
+  _doResumeSession: function sss_doResumeSession() {
+    return this._prefBranch.getIntPref("startup.page") == 3 ||
+      this._prefBranch.getBoolPref("sessionstore.resume_session_once");
+  },
+
+  /**
+   * Are we restarting to switch profile.
+   * @returns bool
+   */
+  _isSwitchingProfile: function sss_isSwitchingProfile() {
+    var env = Cc["@mozilla.org/process/environment;1"]
+                .getService(Ci.nsIEnvironment);
+    return env.exists("XRE_PROFILE_NAME");
+  },
+
+  /**
+   * whether the user wants to load any other page at startup
+   * (except the homepage) - needed for determining whether to overwrite the current tabs
+   * C.f.: nsBrowserContentHandler's defaultArgs implementation.
+   * @returns bool
+   */
+  _isCmdLineEmpty: function sss_isCmdLineEmpty(aWindow) {
+    return "arguments" in aWindow && aWindow.arguments.length &&
+      aWindow.arguments[0] == "about:blank";
+  },
+
+  /**
+   * don't save sensitive data if the user doesn't want to
+   * (distinguishes between encrypted and non-encrypted sites)
+   * @param aIsHTTPS
+   *        Bool is encrypted
+   * @param aUseDefaultPref
+   *        don't do normal check for deferred
+   * @returns bool
+   */
+  _checkPrivacyLevel: function sss_checkPrivacyLevel(aIsHTTPS, aUseDefaultPref) {
+    let pref = "sessionstore.privacy_level";
+    // If we're in the process of quitting and we're not autoresuming the session
+    // then we should treat it as a deferred session. We have a different privacy
+    // pref for that case.
+    if (!aUseDefaultPref && this._loadState == STATE_QUITTING && !this._doResumeSession())
+      pref = "sessionstore.privacy_level_deferred";
+    return this._prefBranch.getIntPref(pref) < (aIsHTTPS ? PRIVACY_ENCRYPTED : PRIVACY_FULL);
+  },
+
+  /**
+   * on popup windows, the XULWindow's attributes seem not to be set correctly
+   * we use thus JSDOMWindow attributes for sizemode and normal window attributes
+   * (and hope for reasonable values when maximized/minimized - since then
+   * outerWidth/outerHeight aren't the dimensions of the restored window)
+   * @param aWindow
+   *        Window reference
+   * @param aAttribute
+   *        String sizemode | width | height | other window attribute
+   * @returns string
+   */
+  _getWindowDimension: function sss_getWindowDimension(aWindow, aAttribute) {
+    var dimension = aWindow[WINDOW_ATTRIBUTES[aAttribute]];
+    if (aAttribute == "sizemode") {
+      switch (dimension) {
+      case aWindow.STATE_MAXIMIZED:
+        return "maximized";
+      case aWindow.STATE_MINIMIZED:
+        return "minimized";
+      default:
+        return "normal";
+      }
+    }
+
+    if (aWindow.windowState == aWindow.STATE_NORMAL) {
+      return dimension;
+    }
+    return aWindow.document.documentElement.getAttribute(aAttribute) || dimension;
+  },
+
+  /**
+   * Get nsIURI from string
+   * @param string
+   * @returns nsIURI
+   */
+  _getURIFromString: function sss_getURIFromString(aString) {
+    return Services.io.newURI(aString);
+  },
+
+  /**
+   * Annotate a breakpad crash report with the currently selected tab's URL.
+   */
+  _updateCrashReportURL: function sss_updateCrashReportURL(aWindow) {
+
+     // If the crash reporter isn't built, we bail out.
+    if (!AppConstants.MOZ_CRASHREPORTER) {
+      return;
+    }
+
+    try {
+      var currentURI = aWindow.getBrowser().currentURI.clone();
+      // if the current URI contains a username/password, remove it
+      try {
+        currentURI.userPass = "";
+      }
+      catch (ex) { } // ignore failures on about: URIs
+
+      Cc["@mozilla.org/xre/app-info;1"]
+        .getService(Ci.nsICrashReporter)
+        .annotateCrashReport("URL", currentURI.spec);
+    }
+    catch (ex) {
+      // don't make noise when crashreporter is built but not enabled
+      if (ex.result != Cr.NS_ERROR_NOT_INITIALIZED)
+        debug(ex);
+    }
+  },
+
+  /**
+   * @param aState is a session state
+   * @param aRecentCrashes is the number of consecutive crashes
+   * @returns whether a restore page will be needed for the session state
+   */
+  _needsRestorePage: function sss_needsRestorePage(aState, aRecentCrashes) {
+    const SIX_HOURS_IN_MS = 6 * 60 * 60 * 1000;
+
+    // don't display the page when there's nothing to restore
+    if (!aState.windows || !aState.windows.length)
+      return false;
+
+    // don't wrap a single about:sessionrestore page
+    let winData = aState.windows;
+    if (winData.length == 1 && winData[0].tabs &&
+        winData[0].tabs.length == 1 && winData[0].tabs[0].entries &&
+        winData[0].tabs[0].entries.length == 1 &&
+        winData[0].tabs[0].entries[0].url == "about:sessionrestore")
+      return false;
+
+    // don't automatically restore in Safe Mode
+    if (Services.appinfo.inSafeMode)
+      return true;
+
+    let max_resumed_crashes =
+      this._prefBranch.getIntPref("sessionstore.max_resumed_crashes");
+    let sessionAge = aState.session && aState.session.lastUpdate &&
+                     (Date.now() - aState.session.lastUpdate);
+
+    return max_resumed_crashes != -1 &&
+           (aRecentCrashes > max_resumed_crashes ||
+            sessionAge && sessionAge >= SIX_HOURS_IN_MS);
+  },
+
+  /**
+   * Determine if the tab state we're passed is something we should save. This
+   * is used when closing a tab or closing a window with a single tab
+   *
+   * @param aTabState
+   *        The current tab state
+   * @returns boolean
+   */
+  _shouldSaveTabState: function sss__shouldSaveTabState(aTabState) {
+    // If the tab has only the transient about:blank history entry, no other
+    // session history, and no userTypedValue, then we don't actually want to
+    // store this tab's data.
+    return aTabState.entries.length &&
+           !(aTabState.entries.length == 1 &&
+             aTabState.entries[0].url == "about:blank" &&
+             !aTabState.userTypedValue);
+  },
+
+  /**
+   * This is going to take a state as provided at startup (via
+   * nsISessionStartup.state) and split it into 2 parts. The first part
+   * (defaultState) will be a state that should still be restored at startup,
+   * while the second part (state) is a state that should be saved for later.
+   * defaultState will be comprised of windows with only pinned tabs, extracted
+   * from state. It will contain the cookies that go along with the history
+   * entries in those tabs. It will also contain window position information.
+   *
+   * defaultState will be restored at startup. state will be placed into
+   * this._lastSessionState and will be kept in case the user explicitly wants
+   * to restore the previous session (publicly exposed as restoreLastSession).
+   *
+   * @param state
+   *        The state, presumably from nsISessionStartup.state
+   * @returns [defaultState, state]
+   */
+  _prepDataForDeferredRestore: function sss__prepDataForDeferredRestore(state) {
+    let defaultState = { windows: [], selectedWindow: 1 };
+
+    state.selectedWindow = state.selectedWindow || 1;
+
+    // Look at each window, remove pinned tabs, adjust selectedindex,
+    // remove window if necessary.
+    for (let wIndex = 0; wIndex < state.windows.length;) {
+      let window = state.windows[wIndex];
+      window.selected = window.selected || 1;
+      // We're going to put the state of the window into this object
+      let pinnedWindowState = { tabs: [], cookies: []};
+      for (let tIndex = 0; tIndex < window.tabs.length;) {
+        if (window.tabs[tIndex].pinned) {
+          // Adjust window.selected
+          if (tIndex + 1 < window.selected)
+            window.selected -= 1;
+          else if (tIndex + 1 == window.selected)
+            pinnedWindowState.selected = pinnedWindowState.tabs.length + 2;
+            // + 2 because the tab isn't actually in the array yet
+
+          // Now add the pinned tab to our window
+          pinnedWindowState.tabs =
+            pinnedWindowState.tabs.concat(window.tabs.splice(tIndex, 1));
+          // We don't want to increment tIndex here.
+          continue;
+        }
+        tIndex++;
+      }
+
+      // At this point the window in the state object has been modified (or not)
+      // We want to build the rest of this new window object if we have pinnedTabs.
+      if (pinnedWindowState.tabs.length) {
+        // First get the other attributes off the window
+        WINDOW_ATTRIBUTES.forEach(function(attr) {
+          if (attr in window) {
+            pinnedWindowState[attr] = window[attr];
+            delete window[attr];
+          }
+        });
+        // We're just copying position data into the pinned window.
+        // Not copying over:
+        // - _closedTabs
+        // - extData
+        // - isPopup
+        // - hidden
+
+        // Assign a unique ID to correlate the window to be opened with the
+        // remaining data
+        window.__lastSessionWindowID = pinnedWindowState.__lastSessionWindowID
+                                     = "" + Date.now() + Math.random();
+
+        // Extract the cookies that belong with each pinned tab
+        this._splitCookiesFromWindow(window, pinnedWindowState);
+
+        // Actually add this window to our defaultState
+        defaultState.windows.push(pinnedWindowState);
+        // Remove the window from the state if it doesn't have any tabs
+        if (!window.tabs.length) {
+         if (wIndex + 1 <= state.selectedWindow)
+            state.selectedWindow -= 1;
+          else if (wIndex + 1 == state.selectedWindow)
+            defaultState.selectedIndex = defaultState.windows.length + 1;
+
+          state.windows.splice(wIndex, 1);
+          // We don't want to increment wIndex here.
+          continue;
+        }
+
+
+      }
+      wIndex++;
+    }
+
+    return [defaultState, state];
+  },
+
+  /**
+   * Splits out the cookies from aWinState into aTargetWinState based on the
+   * tabs that are in aTargetWinState.
+   * This alters the state of aWinState and aTargetWinState.
+   */
+  _splitCookiesFromWindow:
+    function sss_splitCookiesFromWindow(aWinState, aTargetWinState) {
+    if (!aWinState.cookies || !aWinState.cookies.length)
+      return;
+
+    // Get the hosts for history entries in aTargetWinState
+    let cookieHosts = {};
+    aTargetWinState.tabs.forEach(function(tab) {
+      tab.entries.forEach(function(entry) {
+        this._extractHostsForCookiesFromEntry(entry, cookieHosts, false);
+      }, this);
+    }, this);
+
+    // By creating a regex we reduce overhead and there is only one loop pass
+    // through either array (cookieHosts and aWinState.cookies).
+    let hosts = Object.keys(cookieHosts).join("|").replace(/\./g, "\\.");
+    let cookieRegex = new RegExp(".*(" + hosts + ")");
+    for (let cIndex = 0; cIndex < aWinState.cookies.length;) {
+      if (cookieRegex.test(aWinState.cookies[cIndex].host)) {
+        aTargetWinState.cookies =
+          aTargetWinState.cookies.concat(aWinState.cookies.splice(cIndex, 1));
+        continue;
+      }
+      cIndex++;
+    }
+  },
+
+  /**
+   * Converts a JavaScript object into a JSON string
+   * (see http://www.json.org/ for more information).
+   *
+   * The inverse operation consists of JSON.parse(JSON_string).
+   *
+   * @param aJSObject is the object to be converted
+   * @returns the object's JSON representation
+   */
+  _toJSONString: function sss_toJSONString(aJSObject) {
+    return JSON.stringify(aJSObject);
+  },
+
+  _sendRestoreCompletedNotifications: function sss_sendRestoreCompletedNotifications() {
+    // not all windows restored, yet
+    if (this._restoreCount > 1) {
+      this._restoreCount--;
+      return;
+    }
+
+    // observers were already notified
+    if (this._restoreCount == -1)
+      return;
+
+    Services.tm.mainThread.dispatch(this, Ci.nsIThread.DISPATCH_NORMAL);
+
+    this._restoreCount = -1;
+  },
+
+  run: function sss_run() {
+    // This was the last window restored at startup, notify observers.
+    Services.obs.notifyObservers(this.windowToFocus,
+      this._browserSetState ? NOTIFY_BROWSER_STATE_RESTORED : NOTIFY_WINDOWS_RESTORED);
+    this._browserSetState = false;
+  },
+
+  /**
+   * Dispatch an SSWindowState_____ event for the given window.
+   * @param aWindow the window
+   * @param aType the type of event, SSWindowState will be prepended to this string
+   */
+  _sendWindowStateEvent: function sss_sendWindowStateEvent(aWindow, aType) {
+    let event = aWindow.document.createEvent("Events");
+    event.initEvent("SSWindowState" + aType, true, false);
+    aWindow.dispatchEvent(event);
+  },
+
+  /**
+   * Dispatch the SSTabRestored event for the given tab.
+   * @param aTab the which has been restored
+   */
+  _sendTabRestoredNotification: function sss_sendTabRestoredNotification(aTab) {
+    let event = aTab.ownerDocument.createEvent("Events");
+    event.initEvent("SSTabRestored", true, false);
+    aTab.dispatchEvent(event);
+  },
+
+  /**
+   * @param aWindow
+   *        Window reference
+   * @returns whether this window's data is still cached in _statesToRestore
+   *          because it's not fully loaded yet
+   */
+  _isWindowLoaded: function sss_isWindowLoaded(aWindow) {
+    return !aWindow.__SS_restoreID;
+  },
+
+  /**
+   * Replace "Loading..." with the tab label (with minimal side-effects)
+   * @param aString is the string the title is stored in
+   * @param aTabbrowser is a tabbrowser object, containing aTab
+   * @param aTab is the tab whose title we're updating & using
+   *
+   * @returns aString that has been updated with the new title
+   */
+  _replaceLoadingTitle : function sss_replaceLoadingTitle(aString, aTabbrowser, aTab) {
+    if (aString == aTabbrowser.mStringBundle.getString("tabs.loading")) {
+      aTabbrowser.setTabTitle(aTab);
+      [aString, aTab.label] = [aTab.label, aString];
+    }
+    return aString;
+  },
+
+  /**
+   * Resize this._closedWindows to the value of the pref, except in the case
+   * where we don't have any non-popup windows on Windows and Linux. Then we must
+   * resize such that we have at least one non-popup window.
+   */
+  _capClosedWindows : function sss_capClosedWindows() {
+    if (this._closedWindows.length <= this._max_windows_undo)
+      return;
+    let spliceTo = this._max_windows_undo;
+    if (AppConstants.platform != "macosx") {
+      let normalWindowIndex = 0;
+      // try to find a non-popup window in this._closedWindows
+      while (normalWindowIndex < this._closedWindows.length &&
+             this._closedWindows[normalWindowIndex].isPopup)
+        normalWindowIndex++;
+      if (normalWindowIndex >= this._max_windows_undo)
+        spliceTo = normalWindowIndex + 1;
+    }
+
+    this._closedWindows.splice(spliceTo, this._closedWindows.length);
+  },
+
+  /**
+   * Reset state to prepare for a new session state to be restored.
+   */
+  _resetRestoringState: function sss_initRestoringState() {
+    this._tabsToRestore = { visible: [], hidden: [] };
+    this._tabsRestoringCount = 0;
+  },
+
+  /**
+   * Reset the restoring state for a particular tab. This will be called when
+   * removing a tab or when a tab needs to be reset (it's being overwritten).
+   *
+   * @param aTab
+   *        The tab that will be "reset"
+   */
+  _resetTabRestoringState: function sss_resetTabRestoringState(aTab) {
+    let window = aTab.ownerDocument.defaultView;
+    let browser = aTab.linkedBrowser;
+
+    // Keep the tab's previous state for later in this method
+    let previousState = browser.__SS_restoreState;
+
+    // The browser is no longer in any sort of restoring state.
+    delete browser.__SS_restoreState;
+
+    // We want to decrement window.__SS_tabsToRestore here so that we always
+    // decrement it AFTER a tab is done restoring or when a tab gets "reset".
+    window.__SS_tabsToRestore--;
+
+    // Remove the progress listener if we should.
+    this._removeTabsProgressListener(window);
+
+    if (previousState == TAB_STATE_RESTORING) {
+      if (this._tabsRestoringCount)
+        this._tabsRestoringCount--;
+    }
+    else if (previousState == TAB_STATE_NEEDS_RESTORE) {
+      // Make sure the session history listener is removed. This is normally
+      // done in restoreTab, but this tab is being removed before that gets called.
+      this._removeSHistoryListener(aTab);
+
+      // Make sure that the tab is removed from the list of tabs to restore.
+      // Again, this is normally done in restoreTab, but that isn't being called
+      // for this tab.
+      this._removeTabFromTabsToRestore(aTab);
+    }
+  },
+
+  /**
+   * Remove the tab from this._tabsToRestore[visible/hidden]
+   *
+   * @param aTab
+   */
+  _removeTabFromTabsToRestore: function sss_removeTabFromTabsToRestore(aTab) {
+    let arr = this._tabsToRestore[aTab.hidden ? "hidden" : "visible"];
+    let index = arr.indexOf(aTab);
+    if (index > -1)
+      arr.splice(index, 1);
+  },
+
+  /**
+   * Add the tabs progress listener to the window if it isn't already
+   *
+   * @param aWindow
+   *        The window to add our progress listener to
+   */
+  _ensureTabsProgressListener: function sss_ensureTabsProgressListener(aWindow) {
+    let tabbrowser = aWindow.getBrowser();
+    try {
+      tabbrowser.addTabsProgressListener(gRestoreTabsProgressListener);
+    } catch (ex) { }
+  },
+
+  /**
+   * Attempt to remove the tabs progress listener from the window.
+   *
+   * @param aWindow
+   *        The window from which to remove our progress listener from
+   */
+  _removeTabsProgressListener: function sss_removeTabsProgressListener(aWindow) {
+    // If there are no tabs left to restore (or restoring) in this window, then
+    // we can safely remove the progress listener from this window.
+    if (!aWindow.__SS_tabsToRestore)
+      try {
+        aWindow.getBrowser().removeTabsProgressListener(gRestoreTabsProgressListener);
+      } catch (ex) { }
+  },
+
+  /**
+   * Remove the session history listener from the tab's browser if there is one.
+   *
+   * @param aTab
+   *        The tab who's browser to remove the listener
+   */
+  _removeSHistoryListener: function sss_removeSHistoryListener(aTab) {
+    let browser = aTab.linkedBrowser;
+    if (browser.__SS_shistoryListener) {
+      browser.webNavigation.sessionHistory.
+                            removeSHistoryListener(browser.__SS_shistoryListener);
+      delete browser.__SS_shistoryListener;
+    }
+  },
+
+/* ........ Storage API .............. */
+
+  /**
+   * write file to disk
+   * @param aFile
+   *        nsIFile
+   * @param aData
+   *        String data
+   */
+  _writeFile: function sss_writeFile(aFile, aData) {
+    // Initialize the file output stream.
+    var ostream = Cc["@mozilla.org/network/safe-file-output-stream;1"]
+                    .createInstance(Ci.nsIFileOutputStream);
+    ostream.init(aFile, 0x02 | 0x08 | 0x20, parseInt("0600", 8), ostream.DEFER_OPEN);
+
+    // Obtain a converter to convert our data to a UTF-8 encoded input stream.
+    var converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"]
+                      .createInstance(Ci.nsIScriptableUnicodeConverter);
+    converter.charset = "UTF-8";
+
+    // Asynchronously copy the data to the file.
+    var istream = converter.convertToInputStream(aData);
+    var ObserverService = this._observerService;
+    NetUtil.asyncCopy(istream, ostream, function(rc) {
+      if (Components.isSuccessCode(rc)) {
+        Services.obs.notifyObservers(null,
+                                     "sessionstore-state-write-complete");
+      }
+    });
+  }
+};
+
+// A map storing a closed window's state data until it goes aways (is GC'ed).
+// This ensures that API clients can still read (but not write) states of
+// windows they still hold a reference to but we don't.
+var DyingWindowCache = {
+  _data: new WeakMap(),
+
+  has: function (window) {
+    return this._data.has(window);
+  },
+
+  get: function (window) {
+    return this._data.get(window);
+  },
+
+  set: function (window, data) {
+    this._data.set(window, data);
+  },
+
+  remove: function (window) {
+    this._data.delete(window);
+  }
+};
+
+// A weak set of dirty windows. We use it to determine which windows we need to
+// recollect data for when getCurrentState() is called.
+var DirtyWindows = {
+  _data: new WeakMap(),
+
+  has: function (window) {
+    return this._data.has(window);
+  },
+
+  add: function (window) {
+    return this._data.set(window, true);
+  },
+
+  remove: function (window) {
+    this._data.delete(window);
+  },
+
+  clear: function (window) {
+    this._data = new WeakMap();
+  }
+};
+
+// This is used to help meter the number of restoring tabs. This is the control
+// point for telling the next tab to restore. It gets attached to each gBrowser
+// via gBrowser.addTabsProgressListener
+var gRestoreTabsProgressListener = {
+  ss: null,
+  onStateChange: function (aBrowser, aWebProgress, aRequest, aStateFlags, aStatus) {
+    // Ignore state changes on browsers that we've already restored and state
+    // changes that aren't applicable.
+    if (aBrowser.__SS_restoreState == TAB_STATE_RESTORING &&
+        aStateFlags & Ci.nsIWebProgressListener.STATE_STOP &&
+        aStateFlags & Ci.nsIWebProgressListener.STATE_IS_NETWORK &&
+        aStateFlags & Ci.nsIWebProgressListener.STATE_IS_WINDOW) {
+      // We need to reset the tab before starting the next restore.
+      let tab = this.ss._getTabForBrowser(aBrowser);
+      this.ss._resetTabRestoringState(tab);
+      this.ss.restoreNextTab();
+    }
+  }
+}
+
+// A SessionStoreSHistoryListener will be attached to each browser before it is
+// restored. We need to catch reloads that occur before the tab is restored
+// because otherwise, docShell will reload an old URI (usually about:blank).
+function SessionStoreSHistoryListener(ss, aTab) {
+  this.tab = aTab;
+  this.ss = ss;
+}
+
+SessionStoreSHistoryListener.prototype = {
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsISHistoryListener,
+                                         Ci.nsISupportsWeakReference]),
+  browser: null,
+  ss: null,
+  tab: null,
+  OnHistoryNewEntry: function(aNewURI) { },
+  OnHistoryGotoIndex: function(aIndex, aGotoURI) { },
+  OnHistoryPurge: function(aNumEntries) { },
+  OnHistoryReload: function(aReloadURI, aReloadFlags) {
+    // On reload, we want to make sure that session history loads the right
+    // URI. In order to do that, we will just call restoreTab. That will remove
+    // the history listener and load the right URI.
+    this.ss.restoreTab(this.tab);
+    // Returning false will stop the load that docshell is attempting.
+    return false;
+  },
+  OnHistoryReplaceEntry: function(aIndex) { },
+}
+
+
+var NSGetFactory = XPCOMUtils.generateNSGetFactory([SessionStoreService]);