oobe: Fix focus for screens without LoginShelfView buttons

Bug: 1084447
Change-Id: Ifb3ac180c673fff6de349018e649cd0f1d67f847
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2364615Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Commit-Queue: Danila Kuzmin <dkuzmin@google.com>
Cr-Commit-Position: refs/heads/master@{#800175}

ash/login/login_screen_controller.cc

@@ -290,7 +290,7 @@ void LoginScreenController::FocusLoginShelf(bool reverse) {
   Shelf* shelf = Shelf::ForWindow(Shell::Get()->GetPrimaryRootWindow());
   // Tell the focus direction to the status area or the shelf so they can focus
   // the correct child view.
-  if (reverse) {
+  if (reverse || !shelf->shelf_widget()->login_shelf_view()->IsFocusable()) {
     if (!Shell::GetPrimaryRootWindowController()->IsSystemTrayVisible())
       return;
     shelf->GetStatusAreaWidget()

ash/shelf/login_shelf_view.cc

@@ -780,7 +780,18 @@ void LoginShelfView::UpdateUi() {
   // 2. There are Kiosk apps available.
   kiosk_apps_button_->SetVisible(kiosk_apps_button_->HasApps() &&
                                  (is_login_primary || is_oobe));
-
+  // If there is no visible (and thus focusable) buttons, we shouldn't focus
+  // LoginShelfView. We update it here, so we don't need to check visibility
+  // every time we move focus to system tray.
+  bool is_anything_focusable = false;
+  for (auto* child : children()) {
+    if (child->IsFocusable()) {
+      is_anything_focusable = true;
+      break;
+    }
+  }
+  SetFocusBehavior(is_anything_focusable ? views::View::FocusBehavior::ALWAYS
+                                         : views::View::FocusBehavior::NEVER);
   UpdateButtonColors(is_oobe);
   Layout();
 }