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

apps/prefs.cc

 // 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.
 
 #include "apps/prefs.h"
 
 #include "apps/app_launcher.h"
 #include "apps/pref_names.h"
 #include "base/prefs/pref_registry_simple.h"
+#include "components/user_prefs/pref_registry_syncable.h"
 
 namespace apps {
 
 void RegisterPrefs(PrefRegistrySimple* registry) {
   // This pref is a cache of the value from the registry the last time it was
   // checked.
   //
   // During the pref initialization, if it is impossible to synchronously
   // determine whether the app launcher is enabled, assume it is disabled.
   // Anything that needs to know the absolute truth should call
   // GetIsAppLauncherEnabled().
   registry->RegisterBooleanPref(prefs::kAppLauncherIsEnabled, false);
 
 #if defined(OS_WIN)
   registry->RegisterStringPref(prefs::kAppLaunchForMetroRestart, "");
   registry->RegisterStringPref(prefs::kAppLaunchForMetroRestartProfile, "");
   registry->RegisterBooleanPref(prefs::kAppLauncherHasBeenEnabled, false);
 #endif
 
   // Identifies whether we should show the app launcher promo or not.
   // Now that a field trial also controls the showing, so the promo won't show
   // unless the pref is set AND the field trial is set to a proper group.
   registry->RegisterBooleanPref(prefs::kShowAppLauncherPromo, true);
 }
 
+void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry) {
+  // Indicates whether app shortcuts have been created.
+  registry->RegisterBooleanPref(
+      prefs::kShortcutsHaveBeenCreated, false,
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+}
+
 }  // namespace apps