Bug 1867044 - Fire name change for xul labels. r=Jamie

Differential Revision: https://phabricator.services.mozilla.com/D248979

accessible/generic/LocalAccessible.cpp

@@ -1431,9 +1431,9 @@ void LocalAccessible::DOMAttributeChanged(int32_t aNameSpaceID,
   }
 
   // Fire name change and description change events.
-  if (aAttribute == nsGkAtoms::aria_label) {
-    // A valid aria-labelledby would take precedence so an aria-label change
-    // won't change the name.
+  if (aAttribute == nsGkAtoms::aria_label || aAttribute == nsGkAtoms::label) {
+    // A valid aria-labelledby would take precedence over an aria-label or a xul
+    // label attribute. So if that relation exists the name won't change.
     AssociatedElementsIterator iter(mDoc, elm, nsGkAtoms::aria_labelledby);
     if (!iter.NextElem()) {
       mDoc->FireDelayedEvent(nsIAccessibleEvent::EVENT_NAME_CHANGE, this);

accessible/tests/browser/events/browser.toml

@@ -14,6 +14,8 @@ support-files = [
 
 ["browser_menu_and_alerts.js"]
 
+["browser_tab_name_change.js"]
+
 ["browser_test_A11yUtils_announce.js"]
 
 ["browser_test_caret_move_granularity.js"]

accessible/tests/browser/events/browser_tab_name_change.js

@@ -0,0 +1,38 @@
+/* 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";
+
+/* import-globals-from ../../mochitest/role.js */
+loadScripts({ name: "role.js", dir: MOCHITESTS_DIR });
+
+addAccessibleTask(``, async function (browser, _accDoc) {
+  let tabChanged = waitForEvent(
+    EVENT_FOCUS,
+    e => e.accessible.name == "One" && e.accessible.role == ROLE_DOCUMENT
+  );
+
+  // Put new tab in foreground
+  let tab = await BrowserTestUtils.openNewForegroundTab({
+    gBrowser,
+    url: "data:text/html,<title>One</title>",
+  });
+
+  await tabChanged;
+
+  let nameChanged = waitForEvent(
+    EVENT_NAME_CHANGE,
+    e => e.accessible.name == "Two" && e.accessible.role == ROLE_PAGETAB
+  );
+
+  // Change name of background tab
+  BrowserTestUtils.startLoadingURIString(
+    browser,
+    "data:text/html,<title>Two</title>"
+  );
+
+  await nameChanged;
+
+  BrowserTestUtils.removeTab(tab);
+});