diff -r 000000000000 -r 6474c204b198 browser/components/sessionstore/src/TabAttributes.jsm
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/sessionstore/src/TabAttributes.jsm	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,68 @@
+/* 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";
+
+this.EXPORTED_SYMBOLS = ["TabAttributes"];
+
+// A set of tab attributes to persist. We will read a given list of tab
+// attributes when collecting tab data and will re-set those attributes when
+// the given tab data is restored to a new tab.
+this.TabAttributes = Object.freeze({
+  persist: function (name) {
+    return TabAttributesInternal.persist(name);
+  },
+
+  get: function (tab) {
+    return TabAttributesInternal.get(tab);
+  },
+
+  set: function (tab, data = {}) {
+    TabAttributesInternal.set(tab, data);
+  }
+});
+
+let TabAttributesInternal = {
+  _attrs: new Set(),
+
+  // We never want to directly read or write those attributes.
+  // 'image' should not be accessed directly but handled by using the
+  //         gBrowser.getIcon()/setIcon() methods.
+  // 'pending' is used internal by sessionstore and managed accordingly.
+  _skipAttrs: new Set(["image", "pending"]),
+
+  persist: function (name) {
+    if (this._attrs.has(name) || this._skipAttrs.has(name)) {
+      return false;
+    }
+
+    this._attrs.add(name);
+    return true;
+  },
+
+  get: function (tab) {
+    let data = {};
+
+    for (let name of this._attrs) {
+      if (tab.hasAttribute(name)) {
+        data[name] = tab.getAttribute(name);
+      }
+    }
+
+    return data;
+  },
+
+  set: function (tab, data = {}) {
+    // Clear attributes.
+    for (let name of this._attrs) {
+      tab.removeAttribute(name);
+    }
+
+    // Set attributes.
+    for (let name in data) {
+      tab.setAttribute(name, data[name]);
+    }
+  }
+};
+