narrow: Update narrow title for undefined filter views.

Updates `compute_narrow_title` to cover the two cases for views
with undefined filters: "All messages" and "Recent conversations".

Also, moves the call to `notifications.redraw_title` from
`set_narrow_title` and to `update_narrow_title`.

frontend_tests/node_tests/narrow.js

@@ -22,6 +22,9 @@ const compose_pm_pill = mock_esm("../../static/js/compose_pm_pill");
 mock_esm("../../static/js/spectators", {
     login_to_access() {},
 });
+const recent_topics_util = mock_esm("../../static/js/recent_topics_util", {
+    is_visible() {},
+});
 
 function empty_narrow_html(title, html, search_data) {
     const opts = {
@@ -815,10 +818,18 @@ run_test("narrow_to_compose_target PMs", ({override, override_rewire}) => {
     assert.deepEqual(args.operators, [{operator: "is", operand: "private"}]);
 });
 
-run_test("narrow_compute_title", () => {
+run_test("narrow_compute_title", ({override}) => {
     // Only tests cases where the narrow title is different from the filter title.
     let filter;
 
+    // Recent conversations & All messages have `undefined` filter.
+    filter = undefined;
+    override(recent_topics_util, "is_visible", () => true);
+    assert.equal(narrow.compute_narrow_title(filter), "translated: Recent conversations");
+
+    override(recent_topics_util, "is_visible", () => false);
+    assert.equal(narrow.compute_narrow_title(filter), "translated: All messages");
+
     // Search & uncommon narrows
     filter = new Filter([{operator: "search", operand: "potato"}]);
     assert.equal(narrow.compute_narrow_title(filter), "translated: Search results");

frontend_tests/node_tests/recent_topics.js

@@ -102,7 +102,7 @@ mock_esm("../../static/js/user_topics", {
     },
 });
 const narrow = mock_esm("../../static/js/narrow", {
-    set_narrow_title: noop,
+    update_narrow_title: noop,
     hide_mark_as_read_turned_off_banner: noop,
     handle_middle_pane_transition: noop,
     has_shown_message_list_view: true,

static/js/narrow.js

@@ -119,12 +119,20 @@ export function save_pre_narrow_offset_for_reload() {
 export let narrow_title = "home";
 export let has_shown_message_list_view = false;
 
-export function set_narrow_title(title) {
+function set_narrow_title(title) {
     narrow_title = title;
-    notifications.redraw_title();
 }
 
 export function compute_narrow_title(filter) {
+    if (filter === undefined) {
+        // "All messages" and "Recent conversations" views have
+        // an `undefined` filter.
+        if (recent_topics_util.is_visible()) {
+            return $t({defaultMessage: "Recent conversations"});
+        }
+        return $t({defaultMessage: "All messages"});
+    }
+
     const filter_title = filter.get_title();
 
     if (filter_title === undefined) {
@@ -162,9 +170,10 @@ export function compute_narrow_title(filter) {
     return filter_title;
 }
 
-function update_narrow_title(filter) {
+export function update_narrow_title(filter) {
     const narrow_title_string = compute_narrow_title(filter);
     set_narrow_title(narrow_title_string);
+    notifications.redraw_title();
 }
 
 export function reset_ui_state() {
@@ -1007,8 +1016,7 @@ function handle_post_narrow_deactivate_processes() {
     widgetize.set_widgets_for_list();
     typing_events.render_notifications_for_narrow();
     message_view_header.initialize();
-    narrow_title = $t({defaultMessage: "All messages"});
-    notifications.redraw_title();
+    update_narrow_title(narrow_state.filter());
     message_scroll.update_top_of_narrow_notices(message_lists.home);
 }
 

static/js/recent_topics_ui.js

@@ -870,8 +870,7 @@ export function show() {
     compose_closed_ui.update_buttons_for_recent_topics();
 
     narrow_state.reset_current_filter();
-    const recent_topics_title = $t({defaultMessage: "Recent conversations"});
-    narrow.set_narrow_title(recent_topics_title);
+    narrow.update_narrow_title(narrow_state.filter());
     message_view_header.render_title_area();
     narrow.handle_middle_pane_transition();
     pm_list.handle_narrow_deactivated();