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

apps/prefs.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef APPS_PREFS_H_
 #define APPS_PREFS_H_
 
 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_