Fix build error with gcc 4.8.2 about WARN_UNUSED_RESULT

chrome/browser/profiles/profile_impl_io_data.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/profiles/profile_impl_io_data.h"
 
 #include <set>
 #include <string>
 #include <utility>
 
@@ skipping 490 matching lines @@
   main_context->set_cookie_store(cookie_store.get());
 
   // Set up server bound cert service.
   if (!channel_id_service) {
     DCHECK(!lazy_params_->channel_id_path.empty());
 
     scoped_refptr<QuotaPolicyChannelIDStore> channel_id_db =
         new QuotaPolicyChannelIDStore(
             lazy_params_->channel_id_path,
             BrowserThread::GetBlockingPool()->GetSequencedTaskRunner(
-                BrowserThread::GetBlockingPool()->GetSequenceToken()),
+                base::SequencedWorkerPool::GetSequenceToken()),
             lazy_params_->special_storage_policy.get());
     channel_id_service = new net::ChannelIDService(
         new net::DefaultChannelIDStore(channel_id_db.get()),
         base::WorkerPool::GetTaskRunner(true));
   }
 
   set_channel_id_service(channel_id_service);
   main_context->set_channel_id_service(channel_id_service);
 
   scoped_ptr<net::HttpCache::BackendFactory> main_backend(
@@ skipping 252 matching lines @@
     const base::Closure& completion) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(initialized());
 
   DCHECK(transport_security_state());
   // Completes synchronously.
   transport_security_state()->DeleteAllDynamicDataSince(time);
   DCHECK(http_server_properties_manager_);
   http_server_properties_manager_->Clear(completion);
 }