Fix Chrome crashes on calling OnTrayVisibilityChange

ash/common/system/status_area_widget.cc

Index: ash/common/system/status_area_widget.cc
diff --git a/ash/common/system/status_area_widget.cc b/ash/common/system/status_area_widget.cc
index 06bdf90c0d2c21eceda997e746f013cf09ae213d..aebebbafd7f0e95db3f0c5c8a7ff63ba0c5a60d2 100644
--- a/ash/common/system/status_area_widget.cc
+++ b/ash/common/system/status_area_widget.cc
@@ -77,6 +77,8 @@ void StatusAreaWidget::CreateTrayViews() {
   web_notification_tray_->Initialize();
 #if defined(OS_CHROMEOS)
   logout_button_tray_->Initialize();
+  if (palette_tray_)
+    palette_tray_->Initialize();
   virtual_keyboard_tray_->Initialize();
   ime_menu_tray_->Initialize();
 #endif