Fix the flaky test KioskTest.LaunchAppUserCancel

chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <vector>
@@ skipping 119 matching lines @@
   void CancelScheduledCall() { call_scheduled_ = false; }
   void ScheduleCall() { call_scheduled_ = true; }
 
  private:
   base::Closure callback_;
   bool call_scheduled_;
 
   DISALLOW_COPY_AND_ASSIGN(CallOnReturn);
 };
 
+class BoolAutoSet {
+ public:
+  BoolAutoSet(bool* ref, bool val_at_destruct)
+      : bool_ref_(ref),
+        value_at_destruct_(val_at_destruct) {
+  }
+
+  ~BoolAutoSet() {
+    *bool_ref_ = value_at_destruct_;
+  }
+
+ private:
+  bool* bool_ref_;
+  bool value_at_destruct_;
+
+  DISALLOW_COPY_AND_ASSIGN(BoolAutoSet);
+};
+
 }  // namespace
 
 namespace chromeos {
 
 namespace {
 
 bool IsOnline(NetworkStateInformer::State state,
               NetworkError::ErrorReason reason) {
   return state == NetworkStateInformer::ONLINE &&
          reason != NetworkError::ERROR_REASON_PORTAL_DETECTED &&
@@ skipping 754 matching lines @@
   if (last_user_removed)
     OnShowAddUser();
 }
 
 void SigninScreenHandler::OnUserImageChanged(const user_manager::User& user) {
   if (page_is_ready())
     CallJS("login.AccountPickerScreen.updateUserImage", user.GetAccountId());
 }
 
 void SigninScreenHandler::OnPreferencesChanged() {
+  static bool first_preference_changed = true;
+
   // Make sure that one of the login UI is fully functional now, otherwise
   // preferences update would be picked up next time it will be shown.
   if (!webui_visible_) {
     LOG(WARNING) << "Login UI is not active - postponed prefs change.";
     preferences_changed_delayed_ = true;
     return;
   }
 
+  BoolAutoSet at_return_setter(&first_preference_changed, false);
+  preferences_changed_delayed_ = false;
+
+  if (!delegate_)
+    return;
+
   // Send the updated user list to the UI.
-  if (delegate_)
-    delegate_->HandleGetUsers();
+  delegate_->HandleGetUsers();
+  if (GetCurrentScreen() == OobeScreen::SCREEN_ACCOUNT_PICKER &&
+      delegate_->ShowUsersHasChanged() &&
+      !delegate_->IsShowUsers()) {
+    // We are at the account picker screen and the POD setting has changed
+    // to be disabled. We need to show the add user page.
+    HandleShowAddUser(nullptr);
+    return;
+  }
 
-  if (delegate_ && !delegate_->IsShowUsers()) {
-    HandleShowAddUser(nullptr);
-  } else {
+  if (delegate_->AllowNewUserChanged() ||
+      (first_preference_changed && !IsSigninScreen(GetCurrentScreen()))) {

[xiyuan, 2016/06/30 20:21:40]

Can we get rid of |first_preference_changed| and use "ui_state_ ==
UI_STATE_UNKNOWN" ?

If that does not work, let's make first_preference_changed a member instead of
local static.

[afakhry, 2016/07/01 13:14:33]

Done.

+    // We need to reload GAIA if it's the very first preference change and the
+    // current screen is neither GAIA not the account picker or the allow new
+    // user setting has changed so that reloaded GAIA shows/hides the option to
+    // create a new account.
     UpdateUIState(UI_STATE_ACCOUNT_PICKER, nullptr);
   }
-
-  preferences_changed_delayed_ = false;
 }
 
 void SigninScreenHandler::ResetSigninScreenHandlerDelegate() {
   SetDelegate(nullptr);
 }
 
 void SigninScreenHandler::ShowError(int login_attempts,
                                     const std::string& error_text,
                                     const std::string& help_link_text,
                                     HelpAppLauncher::HelpTopic help_topic_id) {
@@ skipping 525 matching lines @@
 }
 
 void SigninScreenHandler::OnFeedbackFinished() {
   CallJS("login.UnrecoverableCryptohomeErrorScreen.resumeAfterFeedbackUI");
 
   // Recreate user's cryptohome after the feedback is attempted.
   HandleResyncUserData();
 }
 
 }  // namespace chromeos