Fixed regression: various preferences were not persisted when changed from incognito window

chrome/browser/policy/configuration_policy_pref_store.cc

 // Copyright (c) 2011 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/policy/configuration_policy_pref_store.h"
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 309 matching lines @@
                                         const Value** result) const {
   const Value* stored_value = NULL;
   if (!prefs_.GetValue(key, &stored_value))
     return PrefStore::READ_NO_VALUE;
 
   // Check whether there's a default value, which indicates READ_USE_DEFAULT
   // should be returned.
   if (stored_value->IsType(Value::TYPE_NULL))
     return PrefStore::READ_USE_DEFAULT;
 
-  *result = stored_value;
+  if (result)
+    *result = stored_value;
   return PrefStore::READ_OK;
 }
 
 void ConfigurationPolicyPrefKeeper::GetDifferingPrefPaths(
     const ConfigurationPolicyPrefKeeper* other,
     std::vector<std::string>* differing_prefs) const {
   prefs_.GetDifferingKeys(&other->prefs_, differing_prefs);
 }
 
 void ConfigurationPolicyPrefKeeper::Apply(ConfigurationPolicyType policy,
@@ skipping 789 matching lines @@
   // Update the initialization flag.
   if (!initialization_complete_ &&
       provider_->IsInitializationComplete()) {
     initialization_complete_ = true;
     FOR_EACH_OBSERVER(PrefStore::Observer, observers_,
                       OnInitializationCompleted(true));
   }
 }
 
 }  // namespace policy