[cros] Initialize OOBE in parallel when boot animation is disabled.

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index f7e2f62410d970c120c2ea57cebd374a6f72467a..a5cf1447dbe23b6d5bab260cf036cdd1a386b8e9 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -458,7 +458,9 @@ void Shell::Init() {
   // Initialize Primary RootWindow specific items.
   status_area_widget_ = new internal::StatusAreaWidget();
   status_area_widget_->CreateTrayViews(delegate_.get());
-  status_area_widget_->Show();
+  // Login screen manages status area visibility by itself.
+  if (delegate_.get() && delegate_->IsSessionStarted())
+    status_area_widget_->Show();
 
   focus_cycler_.reset(new internal::FocusCycler());
   focus_cycler_->AddWidget(status_area_widget_);