Add public accounts to UserManager

chrome/browser/chromeos/settings/cros_settings.cc

 // Copyright (c) 2012 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/settings/cros_settings.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/stl_util.h"
@@ skipping 283 matching lines @@
 void CrosSettings::FireObservers(const std::string& path) {
   DCHECK(CalledOnValidThread());
   SettingsObserverMap::iterator observer_iterator =
       settings_observers_.find(path);
   if (observer_iterator == settings_observers_.end())
     return;
 
   NotificationObserverList::Iterator it(*(observer_iterator->second));
   content::NotificationObserver* observer;
   while ((observer = it.GetNext()) != NULL) {
-    observer->Observe(chrome::NOTIFICATION_SYSTEM_SETTING_CHANGED,
-                      content::Source<CrosSettings>(this),
-                      content::Details<const std::string>(&path));
+    if (observer) {

[pastarmovj, 2012/11/28 09:57:16]

I don't see much sense in this. Why do you need this check and in general this
seems like a wrong use of the observer interface if you have to catch this case
like that.

[bartfab (slow), 2012/11/28 12:30:17]

As discussed offline: I need UserManager to be a CrosSettings observer. Since
UserManager and CrosSettings are both singletons (with undefined shutdown
order), I had to handle both shutdown orders:

* If CrosSettings goes down first, it must accept the fact that UserManager is
still registered as an observer.
* If UserManager goes down first, it must unregister itself as an observer
(problem: it does not know whether CrosSettings is still alive) or invalidate
the observer in some other way (I used WeakPtr for this, necessitating the check
here).

These points are now moot as I added a UserManager::Shutdown() method that gets
called during shutdown and allows the UserManager to unregister cleanly.

+      observer->Observe(chrome::NOTIFICATION_SYSTEM_SETTING_CHANGED,
+                        content::Source<CrosSettings>(this),
+                        content::Details<const std::string>(&path));
+    }
   }
 }
 
 }  // namespace chromeos