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

apps/prefs.cc

Index: apps/prefs.cc
diff --git a/apps/prefs.cc b/apps/prefs.cc
index 9f77687aa1e61e487df7a5655292b6738d1d69ce..4d7ca675c16a7f0eb8be8b82d00ae2312ce0114a 100644
--- a/apps/prefs.cc
+++ b/apps/prefs.cc
@@ -7,6 +7,7 @@
 #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 {
 
@@ -32,4 +33,11 @@ void RegisterPrefs(PrefRegistrySimple* registry) {
   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