Notify ThemeService via callback when supervised user is ready.

chrome/browser/themes/theme_service.h

Index: chrome/browser/themes/theme_service.h
diff --git a/chrome/browser/themes/theme_service.h b/chrome/browser/themes/theme_service.h
index b573d2e6df87c0b42e69be3294e64a90e0076793..653b8112331dc288c569b67988413b9981b1c12d 100644
--- a/chrome/browser/themes/theme_service.h
+++ b/chrome/browser/themes/theme_service.h
@@ -13,6 +13,7 @@
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "base/threading/non_thread_safe.h"
 #include "components/browser_context_keyed_service/browser_context_keyed_service.h"
 #include "content/public/browser/notification_observer.h"
@@ -247,6 +248,8 @@ class ThemeService : public base::NonThreadSafe,
 
   scoped_ptr<ThemeSyncableService> theme_syncable_service_;
 
+  base::WeakPtrFactory<ThemeService> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(ThemeService);
 };