text: /* 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/. */
  
  this.EXPORTED_SYMBOLS = ["PrivateBrowsingUtils"];
  
  Components.utils.import("resource://gre/modules/Services.jsm");
  
  const kAutoStartPref = "browser.privatebrowsing.autostart";
  
  // This will be set to true when the PB mode is autostarted from the command
  // line for the current session.
  let gTemporaryAutoStartMode = false;
  
  const Cc = Components.classes;
  const Ci = Components.interfaces;
  
  this.PrivateBrowsingUtils = {
    isWindowPrivate: function pbu_isWindowPrivate(aWindow) {
      return this.privacyContextFromWindow(aWindow).usePrivateBrowsing;
    },
  
    privacyContextFromWindow: function pbu_privacyContextFromWindow(aWindow) {
      return aWindow.QueryInterface(Ci.nsIInterfaceRequestor)
                    .getInterface(Ci.nsIWebNavigation)
                    .QueryInterface(Ci.nsILoadContext);
    },
  
    get permanentPrivateBrowsing() {
      try {
        return gTemporaryAutoStartMode ||
               Services.prefs.getBoolPref(kAutoStartPref);
      } catch (e) {
        // The pref does not exist
        return false;
      }
    },
  
    // These should only be used from internal code
    enterTemporaryAutoStartMode: function pbu_enterTemporaryAutoStartMode() {
      gTemporaryAutoStartMode = true;
    },
    get isInTemporaryAutoStartMode() {
      return gTemporaryAutoStartMode;
    }
  };
  
  