Wallpaper manager now observing user child user status to update default wallpaper.

chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc

Index: chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
diff --git a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
index 20a9d9801a78f92d6c7b8864ac16e983f6eca9c0..ef44c3902be4dc0fb73a1f9fddc69fbf93d22ff9 100644
--- a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
+++ b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
@@ -307,6 +307,8 @@ WallpaperManager::WallpaperManager()
           base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
   wallpaper_loader_ = new UserImageLoader(ImageDecoder::ROBUST_JPEG_CODEC,
                                           task_runner_);
+
+  user_manager::UserManager::Get()->AddSessionStateObserver(this);
 }
 
 WallpaperManager::~WallpaperManager() {
@@ -314,6 +316,8 @@ WallpaperManager::~WallpaperManager() {
   // http://crbug.com/171694
   DCHECK(!show_user_name_on_signin_subscription_);
 
+  user_manager::UserManager::Get()->RemoveSessionStateObserver(this);
+
   ClearObsoleteWallpaperPrefs();
   weak_factory_.InvalidateWeakPtrs();
 }
@@ -966,6 +970,10 @@ size_t WallpaperManager::GetPendingListSizeForTesting() const {
   return loading_.size();
 }
 
+void WallpaperManager::UserChangedChildStatus(user_manager::User* user) {
+  SetUserWallpaperNow(user->email());
+}
+
 void WallpaperManager::OnDefaultWallpaperDecoded(
     const base::FilePath& path,
     const wallpaper::WallpaperLayout layout,