fix: display empty menu item for non-visible submenus (backport: 5-0-…

…x) (#16848)

* fix: display empty menu item for nonvisible submenus

* use Chromium UI string ID

atom/browser/ui/cocoa/atom_menu_controller.mm

@@ -17,6 +17,7 @@
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/events/cocoa/cocoa_event_utils.h"
 #include "ui/gfx/image/image.h"
+#include "ui/strings/grit/ui_strings.h"
 
 using content::BrowserThread;
 
@@ -58,6 +59,29 @@
     {@selector(clearRecentDocuments:), "clearrecentdocuments"},
 };
 
+// Called when adding a submenu to the menu and checks if the submenu, via its
+// |model|, has visible child items.
+bool MenuHasVisibleItems(const atom::AtomMenuModel* model) {
+  int count = model->GetItemCount();
+  for (int index = 0; index < count; index++) {
+    if (model->IsVisibleAt(index))
+      return true;
+  }
+  return false;
+}
+
+// Called when an empty submenu is created. This inserts a menu item labeled
+// "(empty)" into the submenu. Matches Windows behavior.
+NSMenu* MakeEmptySubmenu() {
+  base::scoped_nsobject<NSMenu> submenu([[NSMenu alloc] initWithTitle:@""]);
+  NSString* empty_menu_title =
+      l10n_util::GetNSString(IDS_APP_MENU_EMPTY_SUBMENU);
+
+  [submenu addItemWithTitle:empty_menu_title action:NULL keyEquivalent:@""];
+  [[submenu itemAtIndex:0] setEnabled:NO];
+  return submenu.autorelease();
+}
+
 }  // namespace
 
 // Menu item is located for ease of removing it from the parent owner
@@ -227,7 +251,9 @@ - (void)addItemToMenu:(NSMenu*)menu
     [item setAction:nil];
     atom::AtomMenuModel* submenuModel =
         static_cast<atom::AtomMenuModel*>(model->GetSubmenuModelAt(index));
-    NSMenu* submenu = [self menuFromModel:submenuModel];
+    NSMenu* submenu = MenuHasVisibleItems(submenuModel)
+                          ? [self menuFromModel:submenuModel]
+                          : MakeEmptySubmenu();
     [submenu setTitle:[item title]];
     [item setSubmenu:submenu];