Add more checks to investigate SupervisedUserPrefStore crash at startup.

chrome/browser/prefs/chrome_pref_service_factory.cc

 // Copyright (c) 2012 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 "chrome/browser/prefs/chrome_pref_service_factory.h"
 
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 423 matching lines @@
           policy::POLICY_LEVEL_MANDATORY)));
   factory->set_recommended_prefs(
       make_scoped_refptr(new ConfigurationPolicyPrefStore(
           policy_service,
           g_browser_process->browser_policy_connector()->GetHandlerList(),
           policy::POLICY_LEVEL_RECOMMENDED)));
 #endif  // ENABLE_CONFIGURATION_POLICY
 
 #if defined(ENABLE_SUPERVISED_USERS)
   if (supervised_user_settings) {
-    factory->set_supervised_user_prefs(
-        make_scoped_refptr(
-            new SupervisedUserPrefStore(supervised_user_settings)));
+    scoped_refptr<PrefStore> supervised_user_prefs = make_scoped_refptr(
+        new SupervisedUserPrefStore(supervised_user_settings));
+    // TODO(bauerb): Temporary CHECK while investigating
+    // https://crbug.com/425785. Remove when that bug is fixed.
+    CHECK(async || supervised_user_prefs->IsInitializationComplete());
+    factory->set_supervised_user_prefs(supervised_user_prefs);
   }
 #endif
 
   factory->set_async(async);
   factory->set_extension_prefs(extension_prefs);
   factory->set_command_line_prefs(make_scoped_refptr(
       new CommandLinePrefStore(base::CommandLine::ForCurrentProcess())));
   factory->set_read_error_callback(base::Bind(&HandleReadError));
   factory->set_user_prefs(user_pref_store);
 }
@@ skipping 112 matching lines @@
 
 void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
   ProfilePrefStoreManager::RegisterProfilePrefs(registry);
 }
 
 void RegisterPrefs(PrefRegistrySimple* registry) {
   ProfilePrefStoreManager::RegisterPrefs(registry);
 }
 
 }  // namespace chrome_prefs