1 files changed, 72 insertions, 0 deletions
diff --git a/browser/components/sessionstore/TabAttributes.sys.mjs b/browser/components/sessionstore/TabAttributes.sys.mjs
new file mode 100644
index 0000000000..1c7f54b6ab
--- /dev/null
+++ b/browser/components/sessionstore/TabAttributes.sys.mjs
@@ -0,0 +1,72 @@
+/* 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/. */
+
+// 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",
+]);
+
+// 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);
+  },
+
+  set(tab, data = {}) {
+    TabAttributesInternal.set(tab, data);
+  },
+});
+
+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) {
+      if (tab.hasAttribute(name)) {
+        data[name] = tab.getAttribute(name);
+      }
+    }
+
+    return data;
+  },
+
+  set(tab, data = {}) {
+    // Clear attributes.
+    for (let name of this._attrs) {
+      tab.removeAttribute(name);
+    }
+
+    // Set attributes.
+    for (let [name, value] of Object.entries(data)) {
+      if (!ATTRIBUTES_TO_SKIP.has(name)) {
+        tab.setAttribute(name, value);
+      }
+    }
+  },
+};