replace NULL->nullptr in src/remoting.

remoting/host/policy_hack/policy_watcher_mac.mm

 // 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 "remoting/host/policy_hack/policy_watcher.h"
 
 #include <CoreFoundation/CoreFoundation.h>
 
 #include "base/compiler_specific.h"
 #include "base/mac/foundation_util.h"
@@ skipping 42 matching lines @@
                                                        policy_bundle_id,
                                                        &valid);
           if (valid) {
             policy.SetBoolean(policy_name, value);
           }
         }
 
         if (i.value().GetType() == base::DictionaryValue::TYPE_STRING) {
           base::ScopedCFTypeRef<CFPropertyListRef> property_list(
               CFPreferencesCopyAppValue(policy_key, policy_bundle_id));
-          if (property_list.get() != NULL) {
+          if (property_list.get() != nullptr) {
             CFStringRef policy_value = base::mac::CFCast<CFStringRef>(
                 property_list.get());
-            if (policy_value != NULL) {
+            if (policy_value != nullptr) {
               policy.SetString(policy_name,
                                base::SysCFStringRefToUTF8(policy_value));
             }
           }
         }
 
       }
     }
 
     // Set policy. Policy must be set (even if it is empty) so that the
     // default policy is picked up the first time reload is called.
     UpdatePolicies(&policy);
 
     // Reschedule task.
     ScheduleFallbackReloadTask();
   }
 };
 
 scoped_ptr<PolicyWatcher> PolicyWatcher::Create(
     policy::PolicyService* policy_service,
     scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
   return make_scoped_ptr(new PolicyWatcherMac(task_runner));
 }
 
 }  // namespace policy_hack
 }  // namespace remoting