OOBE: Refresh GAIA screen upon hide

Fixed: 1067210
Fixed: 1078325
Change-Id: I02b88009f8bf646efbc9d88d1b6e58273f90859c
Bug: 1067210
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2210235
Commit-Queue: Denis Kuznetsov [CET] <antrim@chromium.org>
Auto-Submit: Denis Kuznetsov [CET] <antrim@chromium.org>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#770571}

chrome/browser/chromeos/login/ui/login_display_host_mojo.cc

@@ -282,8 +282,15 @@ void LoginDisplayHostMojo::HideOobeDialog() {
 
   // The dialog can not be hidden if there are no users on the login screen.
   // Reload it instead.
-  if (!login_display_->IsSigninInProgress() && user_count_ == 0) {
+
+  // As ShowDialogCommon will not reload GAIA upon show for performance reasons,
+  // reload it to ensure that no state is persisted between hide and
+  // subsequent show.
+  const bool no_users =
+      !login_display_->IsSigninInProgress() && user_count_ == 0;
+  if (no_users || GetOobeUI()->current_screen() == GaiaView::kScreenId) {
     GetOobeUI()->GetView<GaiaScreenHandler>()->ShowGaiaAsync(EmptyAccountId());
+    if (no_users)
       return;
   }