When app shortcuts are enabled, do a once-off creation of all shortcuts.

apps/prefs.h

Index: apps/prefs.h
diff --git a/apps/prefs.h b/apps/prefs.h
index 373486080e964c2b166904de8d9150da624ebeb0..69cb53559ea2b6d6ed4e2da644f0d35f4d00347b 100644
--- a/apps/prefs.h
+++ b/apps/prefs.h
@@ -7,11 +7,18 @@
 
 class PrefRegistrySimple;
 
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
 namespace apps {
 
 // Register preferences for the apps system.
 void RegisterPrefs(PrefRegistrySimple* registry);
 
+// Register per-profile preferences for the apps system.
+void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry);
+
 }  // namespace apps
 
 #endif  // APPS_PREFS_H_