diff -r 000000000000 -r 6474c204b198 addon-sdk/source/lib/sdk/private-browsing.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/addon-sdk/source/lib/sdk/private-browsing.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,93 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+'use strict';
+
+module.metadata = {
+  "stability": "stable"
+};
+
+const { Ci } = require('chrome');
+const { setMode, getMode, on: onStateChange, isPermanentPrivateBrowsing } = require('./private-browsing/utils');
+const { isWindowPrivate } = require('./window/utils');
+const { emit, on, once, off } = require('./event/core');
+const { when: unload } = require('./system/unload');
+const { deprecateUsage, deprecateFunction, deprecateEvent } = require('./util/deprecate');
+const { getOwnerWindow } = require('./private-browsing/window/utils');
+
+onStateChange('start', function onStart() {
+  emit(exports, 'start');
+});
+
+onStateChange('stop', function onStop() {
+  emit(exports, 'stop');
+});
+
+Object.defineProperty(exports, "isActive", {
+  get: deprecateFunction(getMode, 'require("private-browsing").isActive is deprecated.')
+});
+
+exports.activate = function activate() setMode(true);
+exports.deactivate = function deactivate() setMode(false);
+
+exports.on = deprecateEvents(on.bind(null, exports));
+exports.once = deprecateEvents(once.bind(null, exports));
+exports.removeListener = deprecateEvents(function removeListener(type, listener) {
+  // Note: We can't just bind `off` as we do it for other methods cause skipping
+  // a listener argument will remove all listeners for the given event type
+  // causing misbehavior. This way we make sure all arguments are passed.
+  off(exports, type, listener);
+});
+
+exports.isPrivate = function(thing) {
+  // if thing is defined, and we can find a window for it
+  // then check if the window is private
+  if (!!thing) {
+    // if the thing is a window, and the window is private
+    // then return true
+    if (isWindowPrivate(thing)) {
+      return true;
+    }
+
+    // does the thing have an associated tab?
+    // page-mod instances do..
+    if (thing.tab) {
+      let tabWindow = getOwnerWindow(thing.tab);
+      if (tabWindow) {
+        let isThingPrivate = isWindowPrivate(tabWindow);
+        if (isThingPrivate)
+          return isThingPrivate;
+      }
+    }
+
+    // can we find an associated window?
+    let window = getOwnerWindow(thing);
+    if (window)
+      return isWindowPrivate(window);
+
+    try {
+      let { isChannelPrivate } = thing.QueryInterface(Ci.nsIPrivateBrowsingChannel);
+      if (isChannelPrivate)
+        return true;
+    } catch(e) {}
+  }
+
+  // check if the post pwpb, global pb service is enabled.
+  if (isPermanentPrivateBrowsing())
+    return true;
+
+  // if we get here, and global private browsing
+  // is available, and it is true, then return
+  // true otherwise false is returned here
+  return getMode();
+};
+
+function deprecateEvents(func) deprecateEvent(
+  func,
+   'The require("sdk/private-browsing") module\'s "start" and "stop" events ' +
+   'are deprecated.',
+  ['start', 'stop']
+);
+
+// Make sure listeners are cleaned up.
+unload(function() off(exports));