Hide Apps button after a user session has started

Previously, during the post login steps the Apps button stays visible,
and starting an app crashes the recently started user session.

This is fixed by hiding the Apps button in all post login dialogs.
Hide Apps button after a user session has started

Bug: 1124319
Change-Id: Ie1c1f72c4dd473b928c3f93dc5fbeaf8f03cb30e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2407312
Commit-Queue: Ossama Mahmoud <osamafathy@google.com>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813709}

diff --git a/ash/login/login_screen_controller.cc b/ash/login/login_screen_controller.cc
index ba3ed011e..d0242739 100644
--- a/ash/login/login_screen_controller.cc
+++ b/ash/login/login_screen_controller.cc

@@ -320,11 +320,11 @@
       ->SetShutdownButtonEnabled(enable);
 }
 
-void LoginScreenController::ShowGuestButtonInOobe(bool show) {
+void LoginScreenController::SetIsFirstSigninStep(bool is_first) {
   Shelf::ForWindow(Shell::Get()->GetPrimaryRootWindow())
       ->shelf_widget()
       ->login_shelf_view()
-      ->ShowGuestButtonInOobe(show);
+      ->SetIsFirstSigninStep(is_first);
 }
 
 void LoginScreenController::ShowParentAccessButton(bool show) {