Remove NOTIFICATION_SYSTEM_SETTING_CHANGED, switch CrosSettings to base::CallbackRegistry.

chrome/browser/chromeos/login/user_manager_impl.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/chromeos/login/user_manager_impl.h"
 
 #include <cstddef>
 #include <set>
 
 #include "base/bind.h"
@@ skipping 217 matching lines @@
       ephemeral_users_enabled_(false),
       user_image_manager_(new UserImageManagerImpl),
       manager_creation_time_(base::TimeTicks::Now()) {
   // UserManager instance should be used only on UI thread.
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   registrar_.Add(this, chrome::NOTIFICATION_OWNERSHIP_STATUS_CHANGED,
       content::NotificationService::AllSources());
   registrar_.Add(this, chrome::NOTIFICATION_LOGIN_USER_PROFILE_PREPARED,
       content::NotificationService::AllSources());
   RetrieveTrustedDevicePolicies();
-  cros_settings_->AddSettingsObserver(kAccountsPrefDeviceLocalAccounts,
-                                      this);
-  cros_settings_->AddSettingsObserver(kAccountsPrefSupervisedUsersEnabled,
-                                      this);
+  local_accounts_subscription_ = cros_settings_->AddSettingsObserver(
+      kAccountsPrefDeviceLocalAccounts,
+      base::Bind(&UserManagerImpl::RetrieveTrustedDevicePolicies,
+                 base::Unretained(this)));
+  supervised_users_subscription_ = cros_settings_->AddSettingsObserver(
+      kAccountsPrefSupervisedUsersEnabled,
+      base::Bind(&UserManagerImpl::RetrieveTrustedDevicePolicies,
+                 base::Unretained(this)));
   UpdateLoginState();
 }
 
 UserManagerImpl::~UserManagerImpl() {
   // Can't use STLDeleteElements because of the private destructor of User.
   for (UserList::iterator it = users_.begin(); it != users_.end();
        it = users_.erase(it)) {
     if (active_user_ == *it)
       active_user_ = NULL;
     delete *it;
   }
   // These are pointers to the same User instances that were in users_ list.
   logged_in_users_.clear();
   lru_logged_in_users_.clear();
 
   delete active_user_;
 }
 
 void UserManagerImpl::Shutdown() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  cros_settings_->RemoveSettingsObserver(kAccountsPrefDeviceLocalAccounts,
-                                         this);
-  cros_settings_->RemoveSettingsObserver(
-      kAccountsPrefSupervisedUsersEnabled,
-      this);
+  local_accounts_subscription_.reset();
+  supervised_users_subscription_.reset();
   // Stop the session length limiter.
   session_length_limiter_.reset();
 
   if (device_local_account_policy_service_)
     device_local_account_policy_service_->RemoveObserver(this);
 
   user_image_manager_->Shutdown();
 }
 
 UserImageManager* UserManagerImpl::GetUserImageManager() {
@@ skipping 492 matching lines @@
           !IsLoggedInAsGuest() &&
           !IsLoggedInAsKioskApp()) {
         Profile* profile = content::Details<Profile>(details).ptr();
         if (!profile->IsOffTheRecord()) {
           AuthSyncObserver* sync_observer =
               AuthSyncObserverFactory::GetInstance()->GetForProfile(profile);
           sync_observer->StartObserving();
         }
       }
       break;
-    case chrome::NOTIFICATION_SYSTEM_SETTING_CHANGED: {
-      std::string changed_setting =
-          *content::Details<const std::string>(details).ptr();
-      DCHECK(changed_setting == kAccountsPrefDeviceLocalAccounts ||
-             changed_setting == kAccountsPrefSupervisedUsersEnabled);
-      RetrieveTrustedDevicePolicies();
-      break;
-    }
     default:
       NOTREACHED();
   }
 }
 
 void UserManagerImpl::OnPolicyUpdated(const std::string& user_id) {
   UpdatePublicAccountDisplayName(user_id);
   NotifyUserListChanged();
 }
 
@@ skipping 1005 matching lines @@
         base::TimeTicks::Now() - manager_creation_time_;
     if (!last_email.empty() && email != last_email &&
         time_to_login.InSeconds() <= kLogoutToLoginDelayMaxSec) {
       UMA_HISTOGRAM_CUSTOM_COUNTS("UserManager.LogoutToLoginDelay",
           time_to_login.InSeconds(), 0, kLogoutToLoginDelayMaxSec, 50);
     }
   }
 }
 
 }  // namespace chromeos