Prefer ScopedNestableTaskAllower over manual save/restore

chrome/browser/sync/profile_sync_service_harness.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/sync/profile_sync_service_harness.h"
 
 #include <cstddef>
 #include <iterator>
 #include <ostream>
 #include <set>
@@ skipping 728 matching lines @@
 bool ProfileSyncServiceHarness::AwaitStatusChangeWithTimeout(
     int timeout_milliseconds,
     const std::string& reason) {
   DVLOG(1) << GetClientInfoString("AwaitStatusChangeWithTimeout");
   if (wait_state_ == SYNC_DISABLED) {
     LOG(ERROR) << "Sync disabled for " << profile_debug_name_ << ".";
     return false;
   }
   scoped_refptr<StateChangeTimeoutEvent> timeout_signal(
       new StateChangeTimeoutEvent(this, reason));
-  MessageLoop* loop = MessageLoop::current();
-  bool did_allow_nestable_tasks = loop->NestableTasksAllowed();
-  loop->SetNestableTasksAllowed(true);
-  loop->PostDelayedTask(
-      FROM_HERE,
-      base::Bind(&StateChangeTimeoutEvent::Callback,
-                 timeout_signal.get()),
-      base::TimeDelta::FromMilliseconds(timeout_milliseconds));
-  loop->Run();
-  loop->SetNestableTasksAllowed(did_allow_nestable_tasks);
+  {
+    MessageLoop* loop = MessageLoop::current();
+    MessageLoop::ScopedNestableTaskAllower allow(loop);
+    loop->PostDelayedTask(
+        FROM_HERE,
+        base::Bind(&StateChangeTimeoutEvent::Callback,
+                   timeout_signal.get()),
+        base::TimeDelta::FromMilliseconds(timeout_milliseconds));
+    loop->Run();
+  }
+
   if (timeout_signal->Abort()) {
     DVLOG(1) << GetClientInfoString("AwaitStatusChangeWithTimeout succeeded");
     return true;
   } else {
     DVLOG(0) << GetClientInfoString("AwaitStatusChangeWithTimeout timed out");
     return false;
   }
 }
 
 ProfileSyncService::Status ProfileSyncServiceHarness::GetStatus() {
@@ skipping 347 matching lines @@
   return state_map.size();
 }
 
 std::string ProfileSyncServiceHarness::GetServiceStatus() {
   DictionaryValue value;
   sync_ui_util::ConstructAboutInformation(service_, &value);
   std::string service_status;
   base::JSONWriter::Write(&value, true, &service_status);
   return service_status;
 }