Use TaskScheduler instead of blocking pool in user_policy_manager_factory_chromeos.cc.

The blocking pool is being deprecated in favor of TaskScheduler.

BUG=667892
R=bartfab@chromium.org

Review-Url: https://codereview.chromium.org/2834413003
Cr-Commit-Position: refs/heads/master@{#467728}

chrome/browser/chromeos/policy/user_policy_manager_factory_chromeos.cc

@@ -14,7 +14,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/path_service.h"
 #include "base/sequenced_task_runner.h"
-#include "base/threading/sequenced_worker_pool.h"
+#include "base/task_scheduler/post_task.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "chrome/browser/browser_process.h"
@@ -240,8 +240,12 @@ UserPolicyManagerFactoryChromeOS::CreateManagerForProfile(
           is_active_directory);
 
   scoped_refptr<base::SequencedTaskRunner> backend_task_runner =
-      content::BrowserThread::GetBlockingPool()->GetSequencedTaskRunner(
-          content::BrowserThread::GetBlockingPool()->GetSequenceToken());
+      base::CreateSequencedTaskRunnerWithTraits(
+          base::TaskTraits()
+              .MayBlock()
+              .WithPriority(base::TaskPriority::BACKGROUND)
+              .WithShutdownBehavior(
+                  base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN));
   scoped_refptr<base::SequencedTaskRunner> io_task_runner =
       content::BrowserThread::GetTaskRunnerForThread(
           content::BrowserThread::IO);