Fix build error with gcc 4.8.2 about WARN_UNUSED_RESULT

chrome/browser/search/suggestions/suggestions_service_factory.cc

Index: chrome/browser/search/suggestions/suggestions_service_factory.cc
diff --git a/chrome/browser/search/suggestions/suggestions_service_factory.cc b/chrome/browser/search/suggestions/suggestions_service_factory.cc
index bd65512331401363414f74b9adfac71ffac68999..8a3fd8d966b85890630cecea68e5ac1161aae81c 100644
--- a/chrome/browser/search/suggestions/suggestions_service_factory.cc
+++ b/chrome/browser/search/suggestions/suggestions_service_factory.cc
@@ -57,7 +57,7 @@ KeyedService* SuggestionsServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* profile) const {
   scoped_refptr<base::SequencedTaskRunner> background_task_runner =
       BrowserThread::GetBlockingPool()->GetSequencedTaskRunner(
-          BrowserThread::GetBlockingPool()->GetSequenceToken());
+          base::SequencedWorkerPool::GetSequenceToken());
 
   Profile* the_profile = static_cast<Profile*>(profile);