diff -r 000000000000 -r 6474c204b198 addon-sdk/source/lib/sdk/content/mod.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/addon-sdk/source/lib/sdk/content/mod.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,64 @@
+/* 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": "experimental"
+};
+
+const { Ci } = require("chrome");
+const method = require("../../method/core");
+const { add, remove, iterator } = require("../lang/weak-set");
+
+let getTargetWindow = method("getTargetWindow");
+
+getTargetWindow.define(function (target) {
+  if (target instanceof Ci.nsIDOMWindow)
+    return target;
+  if (target instanceof Ci.nsIDOMDocument)
+    return target.defaultView || null;
+
+  return null;
+});
+
+exports.getTargetWindow = getTargetWindow;
+
+let attachTo = method("attachTo");
+exports.attachTo = attachTo;
+
+let detachFrom = method("detatchFrom");
+exports.detachFrom = detachFrom;
+
+function attach(modification, target) {
+  if (!modification)
+    return;
+
+  let window = getTargetWindow(target);
+
+  attachTo(modification, window);
+
+  // modification are stored per content; `window` reference can still be the
+  // same even if the content is changed, therefore `document` is used instead.
+  add(modification, window.document);
+}
+exports.attach = attach;
+
+function detach(modification, target) {
+  if (!modification)
+    return;
+
+  if (target) {
+    let window = getTargetWindow(target);
+    detachFrom(modification, window);
+    remove(modification, window.document);
+  }
+  else {
+    let documents = iterator(modification);
+    for (let document of documents) {
+      detachFrom(modification, document.defaultView);
+      remove(modification, document);
+    }
+  }
+}
+exports.detach = detach;