Fix GCC build for target 'all'

chrome/browser/previews/previews_service.cc

 // Copyright 2016 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/previews/previews_service.h"
 
 #include "base/files/file_path.h"
 #include "base/memory/ptr_util.h"
 #include "base/sequenced_task_runner.h"
 #include "base/threading/sequenced_worker_pool.h"
@@ skipping 11 matching lines @@
 PreviewsService::~PreviewsService() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 }
 
 void PreviewsService::Initialize(
     previews::PreviewsIOData* previews_io_data,
     const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
     const base::FilePath& profile_path) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
+  base::SequencedWorkerPool* blocking_pool =
+      content::BrowserThread::GetBlockingPool();
   // Get the background thread to run SQLite on.
   scoped_refptr<base::SequencedTaskRunner> background_task_runner =
-      content::BrowserThread::GetBlockingPool()->GetSequencedTaskRunner(
-          content::BrowserThread::GetBlockingPool()->GetSequenceToken());
+      blocking_pool->GetSequencedTaskRunner(blocking_pool->GetSequenceToken());
 
   previews_ui_service_ = base::MakeUnique<previews::PreviewsUIService>(
       previews_io_data, io_task_runner,
       base::MakeUnique<previews::PreviewsOptOutStoreSQL>(
           io_task_runner, background_task_runner,
           profile_path.Append(chrome::kPreviewsOptOutDBFilename)));
 }