Merge commit '50d3e596bbe89c95615f96eb71f6bc5be737a1db' into Basilisk-releasev2018.07.18

# Conflicts:
#	browser/app/profile/firefox.js
#	browser/components/preferences/jar.mn

1 files changed, 742 insertions, 0 deletions

diff --git a/application/basilisk/base/content/browser-addons.js b/application/basilisk/base/content/browser-addons.js
new file mode 100644
index 000000000..1d881536a
--- /dev/null
+++ b/application/basilisk/base/content/browser-addons.js
@@ -0,0 +1,742 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+ * 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/. */
+
+// Removes a doorhanger notification if all of the installs it was notifying
+// about have ended in some way.
+function removeNotificationOnEnd(notification, installs) {
+  let count = installs.length;
+
+  function maybeRemove(install) {
+    install.removeListener(this);
+
+    if (--count == 0) {
+      // Check that the notification is still showing
+      let current = PopupNotifications.getNotification(notification.id, notification.browser);
+      if (current === notification)
+        notification.remove();
+    }
+  }
+
+  for (let install of installs) {
+    install.addListener({
+      onDownloadCancelled: maybeRemove,
+      onDownloadFailed: maybeRemove,
+      onInstallFailed: maybeRemove,
+      onInstallEnded: maybeRemove
+    });
+  }
+}
+
+const gXPInstallObserver = {
+  _findChildShell: function (aDocShell, aSoughtShell)
+  {
+    if (aDocShell == aSoughtShell)
+      return aDocShell;
+
+    var node = aDocShell.QueryInterface(Components.interfaces.nsIDocShellTreeItem);
+    for (var i = 0; i < node.childCount; ++i) {
+      var docShell = node.getChildAt(i);
+      docShell = this._findChildShell(docShell, aSoughtShell);
+      if (docShell == aSoughtShell)
+        return docShell;
+    }
+    return null;
+  },
+
+  _getBrowser: function (aDocShell)
+  {
+    for (let browser of gBrowser.browsers) {
+      if (this._findChildShell(browser.docShell, aDocShell))
+        return browser;
+    }
+    return null;
+  },
+
+  pendingInstalls: new WeakMap(),
+
+  showInstallConfirmation: function(browser, installInfo, height = undefined) {
+    // If the confirmation notification is already open cache the installInfo
+    // and the new confirmation will be shown later
+    if (PopupNotifications.getNotification("addon-install-confirmation", browser)) {
+      let pending = this.pendingInstalls.get(browser);
+      if (pending) {
+        pending.push(installInfo);
+      } else {
+        this.pendingInstalls.set(browser, [installInfo]);
+      }
+      return;
+    }
+
+    let showNextConfirmation = () => {
+      // Make sure the browser is still alive.
+      if (gBrowser.browsers.indexOf(browser) == -1)
+        return;
+
+      let pending = this.pendingInstalls.get(browser);
+      if (pending && pending.length)
+        this.showInstallConfirmation(browser, pending.shift());
+    }
+
+    // If all installs have already been cancelled in some way then just show
+    // the next confirmation
+    if (installInfo.installs.every(i => i.state != AddonManager.STATE_DOWNLOADED)) {
+      showNextConfirmation();
+      return;
+    }
+
+    const anchorID = "addons-notification-icon";
+
+    // Make notifications persist a minimum of 30 seconds
+    var options = {
+      displayURI: installInfo.originatingURI,
+      timeout: Date.now() + 30000,
+    };
+
+    let cancelInstallation = () => {
+      if (installInfo) {
+        for (let install of installInfo.installs) {
+          // The notification may have been closed because the add-ons got
+          // cancelled elsewhere, only try to cancel those that are still
+          // pending install.
+          if (install.state != AddonManager.STATE_CANCELLED)
+            install.cancel();
+        }
+      }
+
+      this.acceptInstallation = null;
+
+      showNextConfirmation();
+    };
+
+    let unsigned = installInfo.installs.filter(i => i.addon.signedState <= AddonManager.SIGNEDSTATE_MISSING);
+    let someUnsigned = unsigned.length > 0 && unsigned.length < installInfo.installs.length;
+
+    options.eventCallback = (aEvent) => {
+      switch (aEvent) {
+        case "removed":
+          cancelInstallation();
+          break;
+        case "shown":
+          let addonList = document.getElementById("addon-install-confirmation-content");
+          while (addonList.firstChild)
+            addonList.firstChild.remove();
+
+          for (let install of installInfo.installs) {
+            let container = document.createElement("hbox");
+
+            let name = document.createElement("label");
+            name.setAttribute("value", install.addon.name);
+            name.setAttribute("class", "addon-install-confirmation-name");
+            container.appendChild(name);
+
+            if (someUnsigned && install.addon.signedState <= AddonManager.SIGNEDSTATE_MISSING) {
+              let unsigned = document.createElement("label");
+              unsigned.setAttribute("value", gNavigatorBundle.getString("addonInstall.unsigned"));
+              unsigned.setAttribute("class", "addon-install-confirmation-unsigned");
+              container.appendChild(unsigned);
+            }
+
+            addonList.appendChild(container);
+          }
+
+          this.acceptInstallation = () => {
+            for (let install of installInfo.installs)
+              install.install();
+            installInfo = null;
+
+            Services.telemetry
+                    .getHistogramById("SECURITY_UI")
+                    .add(Ci.nsISecurityUITelemetry.WARNING_CONFIRM_ADDON_INSTALL_CLICK_THROUGH);
+          };
+          break;
+      }
+    };
+
+    options.learnMoreURL = Services.urlFormatter.formatURLPref("app.support.baseURL");
+
+    let messageString;
+    let notification = document.getElementById("addon-install-confirmation-notification");
+    if (unsigned.length == installInfo.installs.length) {
+      // None of the add-ons are verified
+      messageString = gNavigatorBundle.getString("addonConfirmInstallUnsigned.message");
+      notification.setAttribute("warning", "true");
+      options.learnMoreURL += "unsigned-addons";
+    }
+    else if (unsigned.length == 0) {
+      // All add-ons are verified or don't need to be verified
+      messageString = gNavigatorBundle.getString("addonConfirmInstall.message");
+      notification.removeAttribute("warning");
+      options.learnMoreURL += "find-and-install-add-ons";
+    }
+    else {
+      // Some of the add-ons are unverified, the list of names will indicate
+      // which
+      messageString = gNavigatorBundle.getString("addonConfirmInstallSomeUnsigned.message");
+      notification.setAttribute("warning", "true");
+      options.learnMoreURL += "unsigned-addons";
+    }
+
+    let brandBundle = document.getElementById("bundle_brand");
+    let brandShortName = brandBundle.getString("brandShortName");
+
+    messageString = PluralForm.get(installInfo.installs.length, messageString);
+    messageString = messageString.replace("#1", brandShortName);
+    messageString = messageString.replace("#2", installInfo.installs.length);
+
+    let cancelButton = document.getElementById("addon-install-confirmation-cancel");
+    cancelButton.label = gNavigatorBundle.getString("addonInstall.cancelButton.label");
+    cancelButton.accessKey = gNavigatorBundle.getString("addonInstall.cancelButton.accesskey");
+
+    let acceptButton = document.getElementById("addon-install-confirmation-accept");
+    acceptButton.label = gNavigatorBundle.getString("addonInstall.acceptButton.label");
+    acceptButton.accessKey = gNavigatorBundle.getString("addonInstall.acceptButton.accesskey");
+
+    if (height) {
+      let notification = document.getElementById("addon-install-confirmation-notification");
+      notification.style.minHeight = height + "px";
+    }
+
+    let tab = gBrowser.getTabForBrowser(browser);
+    if (tab) {
+      gBrowser.selectedTab = tab;
+    }
+
+    let popup = PopupNotifications.show(browser, "addon-install-confirmation",
+                                        messageString, anchorID, null, null,
+                                        options);
+
+    removeNotificationOnEnd(popup, installInfo.installs);
+
+    Services.telemetry
+            .getHistogramById("SECURITY_UI")
+            .add(Ci.nsISecurityUITelemetry.WARNING_CONFIRM_ADDON_INSTALL);
+  },
+
+  observe: function (aSubject, aTopic, aData)
+  {
+    var brandBundle = document.getElementById("bundle_brand");
+    var installInfo = aSubject.QueryInterface(Components.interfaces.amIWebInstallInfo);
+    var browser = installInfo.browser;
+
+    // Make sure the browser is still alive.
+    if (!browser || gBrowser.browsers.indexOf(browser) == -1)
+      return;
+
+    const anchorID = "addons-notification-icon";
+    var messageString, action;
+    var brandShortName = brandBundle.getString("brandShortName");
+
+    var notificationID = aTopic;
+    // Make notifications persist a minimum of 30 seconds
+    var options = {
+      displayURI: installInfo.originatingURI,
+      timeout: Date.now() + 30000,
+    };
+
+    switch (aTopic) {
+    case "addon-install-disabled": {
+      notificationID = "xpinstall-disabled";
+
+      if (gPrefService.prefIsLocked("xpinstall.enabled")) {
+        messageString = gNavigatorBundle.getString("xpinstallDisabledMessageLocked");
+        buttons = [];
+      }
+      else {
+        messageString = gNavigatorBundle.getString("xpinstallDisabledMessage");
+
+        action = {
+          label: gNavigatorBundle.getString("xpinstallDisabledButton"),
+          accessKey: gNavigatorBundle.getString("xpinstallDisabledButton.accesskey"),
+          callback: function editPrefs() {
+            gPrefService.setBoolPref("xpinstall.enabled", true);
+          }
+        };
+      }
+
+      PopupNotifications.show(browser, notificationID, messageString, anchorID,
+                              action, null, options);
+      break; }
+    case "addon-install-origin-blocked": {
+      messageString = gNavigatorBundle.getFormattedString("xpinstallPromptMessage",
+                        [brandShortName]);
+
+      let secHistogram = Components.classes["@mozilla.org/base/telemetry;1"].getService(Ci.nsITelemetry).getHistogramById("SECURITY_UI");
+      secHistogram.add(Ci.nsISecurityUITelemetry.WARNING_ADDON_ASKING_PREVENTED);
+      let popup = PopupNotifications.show(browser, notificationID,
+                                          messageString, anchorID,
+                                          null, null, options);
+      removeNotificationOnEnd(popup, installInfo.installs);
+      break; }
+    case "addon-install-blocked": {
+      messageString = gNavigatorBundle.getFormattedString("xpinstallPromptMessage",
+                        [brandShortName]);
+
+      let secHistogram = Components.classes["@mozilla.org/base/telemetry;1"].getService(Ci.nsITelemetry).getHistogramById("SECURITY_UI");
+      action = {
+        label: gNavigatorBundle.getString("xpinstallPromptAllowButton"),
+        accessKey: gNavigatorBundle.getString("xpinstallPromptAllowButton.accesskey"),
+        callback: function() {
+          secHistogram.add(Ci.nsISecurityUITelemetry.WARNING_ADDON_ASKING_PREVENTED_CLICK_THROUGH);
+          installInfo.install();
+        }
+      };
+
+      secHistogram.add(Ci.nsISecurityUITelemetry.WARNING_ADDON_ASKING_PREVENTED);
+      let popup = PopupNotifications.show(browser, notificationID,
+                                          messageString, anchorID,
+                                          action, null, options);
+      removeNotificationOnEnd(popup, installInfo.installs);
+      break; }
+    case "addon-install-started": {
+      let needsDownload = function needsDownload(aInstall) {
+        return aInstall.state != AddonManager.STATE_DOWNLOADED;
+      }
+      // If all installs have already been downloaded then there is no need to
+      // show the download progress
+      if (!installInfo.installs.some(needsDownload))
+        return;
+      notificationID = "addon-progress";
+      messageString = gNavigatorBundle.getString("addonDownloadingAndVerifying");
+      messageString = PluralForm.get(installInfo.installs.length, messageString);
+      messageString = messageString.replace("#1", installInfo.installs.length);
+      options.installs = installInfo.installs;
+      options.contentWindow = browser.contentWindow;
+      options.sourceURI = browser.currentURI;
+      options.eventCallback = (aEvent) => {
+        switch (aEvent) {
+          case "removed":
+            options.contentWindow = null;
+            options.sourceURI = null;
+            break;
+        }
+      };
+      let notification = PopupNotifications.show(browser, notificationID, messageString,
+                                                 anchorID, null, null, options);
+      notification._startTime = Date.now();
+
+      let cancelButton = document.getElementById("addon-progress-cancel");
+      cancelButton.label = gNavigatorBundle.getString("addonInstall.cancelButton.label");
+      cancelButton.accessKey = gNavigatorBundle.getString("addonInstall.cancelButton.accesskey");
+
+      let acceptButton = document.getElementById("addon-progress-accept");
+      if (Preferences.get("xpinstall.customConfirmationUI", false)) {
+        acceptButton.label = gNavigatorBundle.getString("addonInstall.acceptButton.label");
+        acceptButton.accessKey = gNavigatorBundle.getString("addonInstall.acceptButton.accesskey");
+      } else {
+        acceptButton.hidden = true;
+      }
+      break; }
+    case "addon-install-failed": {
+      // TODO This isn't terribly ideal for the multiple failure case
+      for (let install of installInfo.installs) {
+        let host;
+        try {
+          host  = options.displayURI.host;
+        } catch (e) {
+          // displayURI might be missing or 'host' might throw for non-nsStandardURL nsIURIs.
+        }
+
+        if (!host)
+          host = (install.sourceURI instanceof Ci.nsIStandardURL) &&
+                 install.sourceURI.host;
+
+        let error = (host || install.error == 0) ? "addonInstallError" : "addonLocalInstallError";
+        let args;
+        if (install.error < 0) {
+          error += install.error;
+          args = [brandShortName, install.name];
+        } else if (install.addon.blocklistState == Ci.nsIBlocklistService.STATE_BLOCKED) {
+          error += "Blocklisted";
+          args = [install.name];
+        } else {
+          error += "Incompatible";
+          args = [brandShortName, Services.appinfo.version, install.name];
+        }
+
+        // Add Learn More link when refusing to install an unsigned add-on
+        if (install.error == AddonManager.ERROR_SIGNEDSTATE_REQUIRED) {
+          options.learnMoreURL = Services.urlFormatter.formatURLPref("app.support.baseURL") + "unsigned-addons";
+        }
+
+        messageString = gNavigatorBundle.getFormattedString(error, args);
+
+        PopupNotifications.show(browser, notificationID, messageString, anchorID,
+                                action, null, options);
+
+        // Can't have multiple notifications with the same ID, so stop here.
+        break;
+      }
+      this._removeProgressNotification(browser);
+      break; }
+    case "addon-install-confirmation": {
+      let showNotification = () => {
+        let height = undefined;
+
+        if (PopupNotifications.isPanelOpen) {
+          let rect = document.getElementById("addon-progress-notification").getBoundingClientRect();
+          height = rect.height;
+        }
+
+        this._removeProgressNotification(browser);
+        this.showInstallConfirmation(browser, installInfo, height);
+      };
+
+      let progressNotification = PopupNotifications.getNotification("addon-progress", browser);
+      if (progressNotification) {
+        let downloadDuration = Date.now() - progressNotification._startTime;
+        let securityDelay = Services.prefs.getIntPref("security.dialog_enable_delay") - downloadDuration;
+        if (securityDelay > 0) {
+          setTimeout(() => {
+            // The download may have been cancelled during the security delay
+            if (PopupNotifications.getNotification("addon-progress", browser))
+              showNotification();
+          }, securityDelay);
+          break;
+        }
+      }
+      showNotification();
+      break; }
+    case "addon-install-complete": {
+      let needsRestart = installInfo.installs.some(function(i) {
+        return i.addon.pendingOperations != AddonManager.PENDING_NONE;
+      });
+
+      if (needsRestart) {
+        notificationID = "addon-install-restart";
+        messageString = gNavigatorBundle.getString("addonsInstalledNeedsRestart");
+        action = {
+          label: gNavigatorBundle.getString("addonInstallRestartButton"),
+          accessKey: gNavigatorBundle.getString("addonInstallRestartButton.accesskey"),
+          callback: function() {
+            BrowserUtils.restartApplication();
+          }
+        };
+      }
+      else {
+        messageString = gNavigatorBundle.getString("addonsInstalled");
+        action = null;
+      }
+
+      messageString = PluralForm.get(installInfo.installs.length, messageString);
+      messageString = messageString.replace("#1", installInfo.installs[0].name);
+      messageString = messageString.replace("#2", installInfo.installs.length);
+      messageString = messageString.replace("#3", brandShortName);
+
+      // Remove notificaion on dismissal, since it's possible to cancel the
+      // install through the addons manager UI, making the "restart" prompt
+      // irrelevant.
+      options.removeOnDismissal = true;
+
+      PopupNotifications.show(browser, notificationID, messageString, anchorID,
+                              action, null, options);
+      break; }
+    }
+  },
+  _removeProgressNotification(aBrowser) {
+    let notification = PopupNotifications.getNotification("addon-progress", aBrowser);
+    if (notification)
+      notification.remove();
+  }
+};
+
+var LightWeightThemeWebInstaller = {
+  init: function () {
+    let mm = window.messageManager;
+    mm.addMessageListener("LightWeightThemeWebInstaller:Install", this);
+    mm.addMessageListener("LightWeightThemeWebInstaller:Preview", this);
+    mm.addMessageListener("LightWeightThemeWebInstaller:ResetPreview", this);
+  },
+
+  receiveMessage: function (message) {
+    // ignore requests from background tabs
+    if (message.target != gBrowser.selectedBrowser) {
+      return;
+    }
+
+    let data = message.data;
+
+    switch (message.name) {
+      case "LightWeightThemeWebInstaller:Install": {
+        this._installRequest(data.themeData, data.principal, data.baseURI);
+        break;
+      }
+      case "LightWeightThemeWebInstaller:Preview": {
+        this._preview(data.themeData, data.principal, data.baseURI);
+        break;
+      }
+      case "LightWeightThemeWebInstaller:ResetPreview": {
+        this._resetPreview(data && data.principal);
+        break;
+      }
+    }
+  },
+
+  handleEvent: function (event) {
+    switch (event.type) {
+      case "TabSelect": {
+        this._resetPreview();
+        break;
+      }
+    }
+  },
+
+  get _manager () {
+    let temp = {};
+    Cu.import("resource://gre/modules/LightweightThemeManager.jsm", temp);
+    delete this._manager;
+    return this._manager = temp.LightweightThemeManager;
+  },
+
+  _installRequest(dataString, principal, baseURI) {
+    // Don't allow installing off null principals.
+    if (!principal.URI) {
+      return;
+    }
+
+    let data = this._manager.parseTheme(dataString, baseURI);
+
+    if (!data) {
+      return;
+    }
+
+    // A notification bar with the option to undo is normally shown after a
+    // theme is installed.  But the discovery pane served from the url(s)
+    // below has its own toggle switch for quick undos, so don't show the
+    // notification in that case.
+    let notify = this._shouldShowUndoPrompt(principal);
+    if (this._isAllowed(principal)) {
+      this._install(data, notify);
+      return;
+    }
+
+    let allowButtonText =
+      gNavigatorBundle.getString("lwthemeInstallRequest.allowButton");
+    let allowButtonAccesskey =
+      gNavigatorBundle.getString("lwthemeInstallRequest.allowButton.accesskey");
+    let message =
+      gNavigatorBundle.getFormattedString("lwthemeInstallRequest.message",
+                                          [principal.URI.host]);
+    let buttons = [{
+      label: allowButtonText,
+      accessKey: allowButtonAccesskey,
+      callback: function () {
+        LightWeightThemeWebInstaller._install(data, notify);
+      }
+    }];
+
+    this._removePreviousNotifications();
+
+    let notificationBox = gBrowser.getNotificationBox();
+    let notificationBar =
+      notificationBox.appendNotification(message, "lwtheme-install-request", "",
+                                         notificationBox.PRIORITY_INFO_MEDIUM,
+                                         buttons);
+    notificationBar.persistence = 1;
+  },
+
+  _install: function (newLWTheme, notify) {
+    let previousLWTheme = this._manager.currentTheme;
+
+    let listener = {
+      onEnabling: function(aAddon, aRequiresRestart) {
+        if (!aRequiresRestart) {
+          return;
+        }
+
+        let messageString = gNavigatorBundle.getFormattedString("lwthemeNeedsRestart.message",
+          [aAddon.name], 1);
+
+        let action = {
+          label: gNavigatorBundle.getString("lwthemeNeedsRestart.button"),
+          accessKey: gNavigatorBundle.getString("lwthemeNeedsRestart.accesskey"),
+          callback: function () {
+            BrowserUtils.restartApplication();
+          }
+        };
+
+        let options = {
+          timeout: Date.now() + 30000
+        };
+
+        PopupNotifications.show(gBrowser.selectedBrowser, "addon-theme-change",
+                                messageString, "addons-notification-icon",
+                                action, null, options);
+      },
+
+      onEnabled: function(aAddon) {
+        if (notify) {
+          LightWeightThemeWebInstaller._postInstallNotification(newLWTheme, previousLWTheme);
+        }
+      }
+    };
+
+    AddonManager.addAddonListener(listener);
+    this._manager.currentTheme = newLWTheme;
+    AddonManager.removeAddonListener(listener);
+  },
+
+  _postInstallNotification: function (newTheme, previousTheme) {
+    function text(id) {
+      return gNavigatorBundle.getString("lwthemePostInstallNotification." + id);
+    }
+
+    let buttons = [{
+      label: text("undoButton"),
+      accessKey: text("undoButton.accesskey"),
+      callback: function () {
+        LightWeightThemeWebInstaller._manager.forgetUsedTheme(newTheme.id);
+        LightWeightThemeWebInstaller._manager.currentTheme = previousTheme;
+      }
+    }, {
+      label: text("manageButton"),
+      accessKey: text("manageButton.accesskey"),
+      callback: function () {
+        BrowserOpenAddonsMgr("addons://list/theme");
+      }
+    }];
+
+    this._removePreviousNotifications();
+
+    let notificationBox = gBrowser.getNotificationBox();
+    let notificationBar =
+      notificationBox.appendNotification(text("message"),
+                                         "lwtheme-install-notification", "",
+                                         notificationBox.PRIORITY_INFO_MEDIUM,
+                                         buttons);
+    notificationBar.persistence = 1;
+    notificationBar.timeout = Date.now() + 20000; // 20 seconds
+  },
+
+  _removePreviousNotifications: function () {
+    let box = gBrowser.getNotificationBox();
+
+    ["lwtheme-install-request",
+     "lwtheme-install-notification"].forEach(function (value) {
+        let notification = box.getNotificationWithValue(value);
+        if (notification)
+          box.removeNotification(notification);
+      });
+  },
+
+  _preview(dataString, principal, baseURI) {
+    if (!this._isAllowed(principal))
+      return;
+
+    let data = this._manager.parseTheme(dataString, baseURI);
+    if (!data)
+      return;
+
+    this._resetPreview();
+    gBrowser.tabContainer.addEventListener("TabSelect", this, false);
+    this._manager.previewTheme(data);
+  },
+
+  _resetPreview(principal) {
+    if (!this._isAllowed(principal))
+      return;
+    gBrowser.tabContainer.removeEventListener("TabSelect", this, false);
+    this._manager.resetPreview();
+  },
+
+  _isAllowed(principal) {
+    if (!principal || !principal.URI || !principal.URI.schemeIs("https")) {
+      return false;
+    }
+
+    let pm = Services.perms;
+    return pm.testPermission(principal.URI, "install") == pm.ALLOW_ACTION;
+  },
+
+  _shouldShowUndoPrompt(principal) {
+    if (!principal || !principal.URI) {
+      return true;
+    }
+
+    let prePath = principal.URI.prePath;
+    if (prePath == "https://addons.palemoon.org") {
+      return false;
+    }
+
+    return true;
+  }
+};
+
+/*
+ * Listen for Lightweight Theme styling changes and update the browser's theme accordingly.
+ */
+var LightweightThemeListener = {
+  _modifiedStyles: [],
+
+  init: function () {
+    XPCOMUtils.defineLazyGetter(this, "styleSheet", function() {
+      for (let i = document.styleSheets.length - 1; i >= 0; i--) {
+        let sheet = document.styleSheets[i];
+        if (sheet.href == "chrome://browser/skin/browser-lightweightTheme.css")
+          return sheet;
+      }
+      return undefined;
+    });
+
+    Services.obs.addObserver(this, "lightweight-theme-styling-update", false);
+    Services.obs.addObserver(this, "lightweight-theme-optimized", false);
+    if (document.documentElement.hasAttribute("lwtheme"))
+      this.updateStyleSheet(document.documentElement.style.backgroundImage);
+  },
+
+  uninit: function () {
+    Services.obs.removeObserver(this, "lightweight-theme-styling-update");
+    Services.obs.removeObserver(this, "lightweight-theme-optimized");
+  },
+
+  /**
+   * Append the headerImage to the background-image property of all rulesets in
+   * browser-lightweightTheme.css.
+   *
+   * @param headerImage - a string containing a CSS image for the lightweight theme header.
+   */
+  updateStyleSheet: function(headerImage) {
+    if (!this.styleSheet)
+      return;
+    this.substituteRules(this.styleSheet.cssRules, headerImage);
+  },
+
+  substituteRules: function(ruleList, headerImage, existingStyleRulesModified = 0) {
+    let styleRulesModified = 0;
+    for (let i = 0; i < ruleList.length; i++) {
+      let rule = ruleList[i];
+      if (rule instanceof Ci.nsIDOMCSSGroupingRule) {
+        // Add the number of modified sub-rules to the modified count
+        styleRulesModified += this.substituteRules(rule.cssRules, headerImage, existingStyleRulesModified + styleRulesModified);
+      } else if (rule instanceof Ci.nsIDOMCSSStyleRule) {
+        if (!rule.style.backgroundImage)
+          continue;
+        let modifiedIndex = existingStyleRulesModified + styleRulesModified;
+        if (!this._modifiedStyles[modifiedIndex])
+          this._modifiedStyles[modifiedIndex] = { backgroundImage: rule.style.backgroundImage };
+
+        rule.style.backgroundImage = this._modifiedStyles[modifiedIndex].backgroundImage + ", " + headerImage;
+        styleRulesModified++;
+      } else {
+        Cu.reportError("Unsupported rule encountered");
+      }
+    }
+    return styleRulesModified;
+  },
+
+  // nsIObserver
+  observe: function (aSubject, aTopic, aData) {
+    if ((aTopic != "lightweight-theme-styling-update" && aTopic != "lightweight-theme-optimized") ||
+          !this.styleSheet)
+      return;
+
+    if (aTopic == "lightweight-theme-optimized" && aSubject != window)
+      return;
+
+    let themeData = JSON.parse(aData);
+    if (!themeData)
+      return;
+    this.updateStyleSheet("url(" + themeData.headerURL + ")");
+  },
+};