[Merge to M50] Enable bootstrapping feature by default.

chrome/browser/chromeos/login/existing_user_controller_browsertest.cc

Index: chrome/browser/chromeos/login/existing_user_controller_browsertest.cc
diff --git a/chrome/browser/chromeos/login/existing_user_controller_browsertest.cc b/chrome/browser/chromeos/login/existing_user_controller_browsertest.cc
index fd45ed8abea88f56367ed9231346d352abd1af89..7d257ebe3bbfcce4b7c5115ca337dcb27843ae14 100644
--- a/chrome/browser/chromeos/login/existing_user_controller_browsertest.cc
+++ b/chrome/browser/chromeos/login/existing_user_controller_browsertest.cc
@@ -418,6 +418,10 @@ class ExistingUserControllerPublicSessionTest
     WizardController* controller = WizardController::default_controller();
     if (controller && controller->current_screen())
       controller->current_screen()->Hide();
+
+    if (LoginDisplayHost::default_host())
+      LoginDisplayHost::default_host()->Finalize();
+    base::MessageLoop::current()->RunUntilIdle();
   }
 
   void ExpectSuccessfulLogin(const UserContext& user_context) {