1 files changed, 7 insertions, 36 deletions
diff --git a/browser/components/sessionstore/TabAttributes.sys.mjs b/browser/components/sessionstore/TabAttributes.sys.mjs
index 1c7f54b6ab..ea53156d12 100644
--- a/browser/components/sessionstore/TabAttributes.sys.mjs
+++ b/browser/components/sessionstore/TabAttributes.sys.mjs
@@ -2,27 +2,13 @@
  * 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/. */
 
-// We never want to directly read or write these attributes.
-// 'image' should not be accessed directly but handled by using the
-//         gBrowser.getIcon()/setIcon() methods.
-// 'muted' should not be accessed directly but handled by using the
-//         tab.linkedBrowser.audioMuted/toggleMuteAudio methods.
-// 'pending' is used internal by sessionstore and managed accordingly.
-const ATTRIBUTES_TO_SKIP = new Set([
-  "image",
-  "muted",
-  "pending",
-  "skipbackgroundnotify",
-]);
+// Tab attributes which are persisted & restored by SessionStore.
+const PERSISTED_ATTRIBUTES = ["customizemode"];
 
 // 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.
 export var TabAttributes = Object.freeze({
-  persist(name) {
-    return TabAttributesInternal.persist(name);
-  },
-
   get(tab) {
     return TabAttributesInternal.get(tab);
   },
@@ -33,21 +19,10 @@ export var TabAttributes = Object.freeze({
 });
 
 var TabAttributesInternal = {
-  _attrs: new Set(),
-
-  persist(name) {
-    if (this._attrs.has(name) || ATTRIBUTES_TO_SKIP.has(name)) {
-      return false;
-    }
-
-    this._attrs.add(name);
-    return true;
-  },
-
   get(tab) {
     let data = {};
 
-    for (let name of this._attrs) {
+    for (let name of PERSISTED_ATTRIBUTES) {
       if (tab.hasAttribute(name)) {
         data[name] = tab.getAttribute(name);
       }
@@ -57,15 +32,11 @@ var TabAttributesInternal = {
   },
 
   set(tab, data = {}) {
-    // Clear attributes.
-    for (let name of this._attrs) {
+    // Clear & Set attributes.
+    for (let name of PERSISTED_ATTRIBUTES) {
       tab.removeAttribute(name);
-    }
-
-    // Set attributes.
-    for (let [name, value] of Object.entries(data)) {
-      if (!ATTRIBUTES_TO_SKIP.has(name)) {
-        tab.setAttribute(name, value);
+      if (name in data) {
+        tab.setAttribute(name, data[name]);
       }
     }
   },