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

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

Index: chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
diff --git a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
index 14eec185d486fbeb565ba1e68aaf22b9a1468d72..536d752dcfb088f21aec427677d048e5cf58592c 100644
--- a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
+++ b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
@@ -21,6 +21,7 @@
 #include "chrome/browser/chromeos/settings/cros_settings.h"
 #include "components/user_manager/user.h"
 #include "components/user_manager/user_image/user_image.h"
+#include "components/user_manager/user_manager.h"
 #include "components/wallpaper/wallpaper_layout.h"
 #include "components/wallpaper/wallpaper_manager_base.h"
 #include "content/public/browser/notification_observer.h"
@@ -30,7 +31,9 @@
 
 namespace chromeos {
 
-class WallpaperManager : public wallpaper::WallpaperManagerBase {
+class WallpaperManager :
+    public wallpaper::WallpaperManagerBase,
+    public user_manager::UserManager::UserSessionStateObserver {
  public:
   class PendingWallpaper;
 
@@ -115,6 +118,9 @@ class WallpaperManager : public wallpaper::WallpaperManagerBase {
   // Returns queue size.
   size_t GetPendingListSizeForTesting() const override;
 
+  // Overridden from user_manager::UserManager::UserSessionStateObserver:
+  void UserChangedChildStatus(user_manager::User* user) override;
+
  private:
   friend class TestApi;
   friend class WallpaperManagerBrowserTest;