Bug 1755181 - Reload sidebar contents on app locale change; r=platform-i18n-reviewers,nordzilla

Differential Revision: https://phabricator.services.mozilla.com/D140665

browser/base/content/browser-sidebar.js

@@ -116,6 +116,8 @@ var SidebarUI = {
 
     this._inited = true;
 
+    Services.obs.addObserver(this, "intl:app-locales-changed");
+
     this._initDeferred.resolve();
   },
 
@@ -146,12 +148,32 @@ var SidebarUI = {
       xulStore.persist(this._title, "value");
     }
 
+    Services.obs.removeObserver(this, "intl:app-locales-changed");
+
     if (this._observer) {
       this._observer.disconnect();
       this._observer = null;
     }
   },
 
+  /**
+   * The handler for Services.obs.addObserver.
+   **/
+  observe(_subject, topic, _data) {
+    switch (topic) {
+      case "intl:app-locales-changed": {
+        if (this.isOpen) {
+          // The <tree> component used in history and bookmarks, but it does not
+          // support live switching the app locale. Reload the entire sidebar to
+          // invalidate any old text.
+          this.hide();
+          this._show(this.lastOpenedId);
+          break;
+        }
+      }
+    }
+  },
+
   /**
    * Ensure the title stays in sync with the source element, which updates for
    * l10n changes.

browser/base/content/test/sidebar/browser.ini

@@ -1,6 +1,7 @@
 [DEFAULT]
 
 [browser_sidebar_adopt.js]
+[browser_sidebar_app_locale_changed.js]
 [browser_sidebar_keys.js]
 [browser_sidebar_move.js]
 [browser_sidebar_switcher.js]

browser/base/content/test/sidebar/browser_sidebar_app_locale_changed.js

@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * This file tests that the sidebar recreates the contents of the <tree> element
+ * for live app locale switching.
+ */
+
+add_task(function cleanup() {
+  registerCleanupFunction(() => {
+    SidebarUI.hide();
+  });
+});
+
+/**
+ * @param {string} sidebarName
+ */
+async function testLiveReloading(sidebarName) {
+  info("Showing the sidebar " + sidebarName);
+  await SidebarUI.show(sidebarName);
+
+  function getTreeChildren() {
+    const sidebarDoc = document.querySelector("#sidebar").contentWindow
+      .document;
+    return sidebarDoc.querySelector(".sidebar-placesTreechildren");
+  }
+
+  const childrenBefore = getTreeChildren();
+  ok(childrenBefore, "Found the sidebar children");
+  is(childrenBefore, getTreeChildren(), "The children start out as equal");
+
+  info("Simulating an app locale change.");
+  Services.obs.notifyObservers(null, "intl:app-locales-changed");
+
+  await TestUtils.waitForCondition(
+    getTreeChildren,
+    "Waiting for a new child tree element."
+  );
+
+  isnot(
+    childrenBefore,
+    getTreeChildren(),
+    "The tree's contents are re-computed."
+  );
+
+  info("Hiding the sidebar");
+  SidebarUI.hide();
+}
+
+add_task(async function test_bookmarks_sidebar() {
+  await testLiveReloading("viewBookmarksSidebar");
+});
+
+add_task(async function test_history_sidebar() {
+  await testLiveReloading("viewHistorySidebar");
+});