Remove NOTIFICATION_SYSTEM_SETTING_CHANGED, switch CrosSettings to base::CallbackRegistry.

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 "base/callback.h"
 #include "base/chromeos/chromeos_version.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 385 matching lines @@
       error_screen_actor_(error_screen_actor),
       core_oobe_actor_(core_oobe_actor),
       is_first_update_state_call_(true),
       offline_login_active_(false),
       last_network_state_(NetworkStateInformer::UNKNOWN),
       has_pending_auth_ui_(false) {
   DCHECK(network_state_informer_.get());
   DCHECK(error_screen_actor_);
   DCHECK(core_oobe_actor_);
   network_state_informer_->AddObserver(this);
-  CrosSettings::Get()->AddSettingsObserver(kAccountsPrefAllowNewUser, this);
-  CrosSettings::Get()->AddSettingsObserver(kAccountsPrefAllowGuest, this);
+  allow_new_user_subscription_ = CrosSettings::Get()->AddSettingsObserver(
+      kAccountsPrefAllowNewUser,
+      base::Bind(&SigninScreenHandler::UserSettingsChanged,
+                 base::Unretained(this)));
+  allow_guest_subscription_ = CrosSettings::Get()->AddSettingsObserver(
+      kAccountsPrefAllowGuest,
+      base::Bind(&SigninScreenHandler::UserSettingsChanged,
+                 base::Unretained(this)));
 
   registrar_.Add(this,
                  chrome::NOTIFICATION_AUTH_NEEDED,
                  content::NotificationService::AllSources());
   registrar_.Add(this,
                  chrome::NOTIFICATION_AUTH_SUPPLIED,
                  content::NotificationService::AllSources());
   registrar_.Add(this,
                  chrome::NOTIFICATION_AUTH_CANCELLED,
                  content::NotificationService::AllSources());
 }
 
 SigninScreenHandler::~SigninScreenHandler() {
   weak_factory_.InvalidateWeakPtrs();
   SystemKeyEventListener* key_event_listener =
       SystemKeyEventListener::GetInstance();
   if (key_event_listener)
     key_event_listener->RemoveCapsLockObserver(this);
   if (delegate_)
     delegate_->SetWebUIHandler(NULL);
   network_state_informer_->RemoveObserver(this);
-  CrosSettings::Get()->RemoveSettingsObserver(kAccountsPrefAllowNewUser, this);
-  CrosSettings::Get()->RemoveSettingsObserver(kAccountsPrefAllowGuest, this);
 }
 
 void SigninScreenHandler::DeclareLocalizedValues(
     LocalizedValuesBuilder* builder) {
   builder->Add("signinScreenTitle", IDS_SIGNIN_SCREEN_TITLE);
   builder->Add("signinScreenPasswordChanged",
                IDS_SIGNIN_SCREEN_PASSWORD_CHANGED);
   builder->Add("passwordHint", IDS_LOGIN_POD_EMPTY_PASSWORD_TEXT);
   builder->Add("podMenuButtonAccessibleName",
                IDS_LOGIN_POD_MENU_BUTTON_ACCESSIBLE_NAME);
@@ skipping 545 matching lines @@
 
 void SigninScreenHandler::OnCapsLockChange(bool enabled) {
   if (page_is_ready())
     CallJS("login.AccountPickerScreen.setCapsLockState", enabled);
 }
 
 void SigninScreenHandler::Observe(int type,
                                   const content::NotificationSource& source,
                                   const content::NotificationDetails& details) {
   switch (type) {
-    case chrome::NOTIFICATION_SYSTEM_SETTING_CHANGED: {
-      UpdateAuthExtension();
-      UpdateAddButtonStatus();
-      break;
-    }
     case chrome::NOTIFICATION_AUTH_NEEDED: {
       has_pending_auth_ui_ = true;
       break;
     }
     case chrome::NOTIFICATION_AUTH_SUPPLIED:
       has_pending_auth_ui_ = false;
       if (IsSigninScreenHiddenByError()) {
         // Hide error screen and reload auth extension.
         HideOfflineMessage(network_state_informer_->state(),
                            ErrorScreenActor::ERROR_REASON_PROXY_AUTH_SUPPLIED);
@@ skipping 163 matching lines @@
       CommandLine::ForCurrentProcess()->HasSwitch(::switches::kGaiaUrl) ?
           GURL(CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
                     ::switches::kGaiaUrl)) :
           GaiaUrls::GetInstance()->gaia_url();
   params.SetString("gaiaUrl", gaia_url.spec());
 
   frame_state_ = FRAME_STATE_LOADING;
   CallJS("login.GaiaSigninScreen.loadAuthExtension", params);
 }
 
+void SigninScreenHandler::UserSettingsChanged() {
+  UpdateAuthExtension();
+  UpdateAddButtonStatus();
+}
+
 void SigninScreenHandler::UpdateAuthExtension() {
   DictionaryValue params;
   UpdateAuthParams(&params);
   CallJS("login.GaiaSigninScreen.updateAuthExtension", params);
 }
 
 void SigninScreenHandler::UpdateAddButtonStatus() {
   CallJS("cr.ui.login.DisplayManager.updateAddUserButtonStatus",
          AllWhitelistedUsersPresent());
 }
@@ skipping 574 matching lines @@
   rvh->ExecuteJavascriptInWebFrame(
       ASCIIToUTF16("//iframe[@id='signin-frame']\n//iframe"),
       ASCIIToUTF16(code));
 
   // Test properties are cleared in HandleCompleteLogin because the form
   // submission might fail and login will not be attempted after reloading
   // if they are cleared here.
 }
 
 }  // namespace chromeos