Remove NOTIFICATION_SYSTEM_SETTING_CHANGED, switch CrosSettings to base::CallbackRegistry.

chrome/browser/chromeos/login/wallpaper_manager.cc

Index: chrome/browser/chromeos/login/wallpaper_manager.cc
diff --git a/chrome/browser/chromeos/login/wallpaper_manager.cc b/chrome/browser/chromeos/login/wallpaper_manager.cc
index 10bf168a15d71bfc89f8c11cbc0e02e5189a4e4e..5bfbdb577eb450bbc109412be981dba21a6908fa 100644
--- a/chrome/browser/chromeos/login/wallpaper_manager.cc
+++ b/chrome/browser/chromeos/login/wallpaper_manager.cc
@@ -162,8 +162,7 @@ WallpaperManager::~WallpaperManager() {
 }
 
 void WallpaperManager::Shutdown() {
-  CrosSettings::Get()->RemoveSettingsObserver(
-      kAccountsPrefShowUserNamesOnSignIn, this);
+  show_user_name_on_signin_subscription_.reset();
   no_observers_ = true;

[Mattias Nissler (ping if slow), 2013/09/18 09:09:48]

You probably want to nuke |no_observers_| and replace the DCHECK in line 159
with DCHECK(!show_user_name_on_signin_subscription_).

[Avi (use Gerrit), 2013/09/18 16:41:44]

Done.

 }
 
@@ -175,8 +174,11 @@ void WallpaperManager::RegisterPrefs(PrefRegistrySimple* registry) {
 }
 
 void WallpaperManager::AddObservers() {
-  CrosSettings::Get()->AddSettingsObserver(kAccountsPrefShowUserNamesOnSignIn,
-                                           this);
+  show_user_name_on_signin_subscription_ =
+      CrosSettings::Get()->AddSettingsObserver(
+          kAccountsPrefShowUserNamesOnSignIn,
+          base::Bind(&WallpaperManager::InitializeRegisteredDeviceWallpaper,
+                     base::Unretained(this)));
   no_observers_ = false;
 }
 
@@ -324,13 +326,6 @@ void WallpaperManager::Observe(int type,
       }
       break;
     }
-    case chrome::NOTIFICATION_SYSTEM_SETTING_CHANGED: {
-      if (*content::Details<const std::string>(details).ptr() ==
-          kAccountsPrefShowUserNamesOnSignIn) {
-        InitializeRegisteredDeviceWallpaper();
-      }
-      break;
-    }
     default:
       NOTREACHED() << "Unexpected notification " << type;
   }