Use TaskScheduler instead of SequencedWorkerPool in session_manager_operation.cc.

chrome/browser/chromeos/settings/session_manager_operation.cc

Index: chrome/browser/chromeos/settings/session_manager_operation.cc
diff --git a/chrome/browser/chromeos/settings/session_manager_operation.cc b/chrome/browser/chromeos/settings/session_manager_operation.cc
index efbcdd8e491b1e715abbc6cc7841364d4a952f59..34ea78d7fe0e094c14322f9d7c68c1f00c439786 100644
--- a/chrome/browser/chromeos/settings/session_manager_operation.cc
+++ b/chrome/browser/chromeos/settings/session_manager_operation.cc
@@ -14,13 +14,11 @@
 #include "base/stl_util.h"
 #include "base/task_runner_util.h"
 #include "base/task_scheduler/post_task.h"
-#include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/chromeos/policy/proto/chrome_device_policy.pb.h"
 #include "chrome/browser/net/nss_context.h"
 #include "components/ownership/owner_key_util.h"
 #include "components/policy/core/common/cloud/cloud_policy_constants.h"
 #include "components/policy/proto/device_management_backend.pb.h"
-#include "content/public/browser/browser_thread.h"
 #include "crypto/rsa_private_key.h"
 #include "crypto/signature_creator.h"
 
@@ -162,12 +160,10 @@ void SessionManagerOperation::ValidateDeviceSettings(
     return;
   }
 
-  base::SequencedWorkerPool* pool =
-      content::BrowserThread::GetBlockingPool();
   scoped_refptr<base::SequencedTaskRunner> background_task_runner =
-      pool->GetSequencedTaskRunnerWithShutdownBehavior(
-          pool->GetSequenceToken(),
-          base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
+      base::CreateSequencedTaskRunnerWithTraits(
+          {base::MayBlock(), base::TaskPriority::BACKGROUND,

[bartfab (slow), 2017/06/12 15:05:48]

Nit: #include "base/task_scheduler/task_traits.h"

[bartfab (slow), 2017/06/12 15:08:07]

I think this should be base::TaskPriority::USER_BLOCKING. We use this background
task runner to validate policy. This validation blocks the login flow.

+           base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN});
 
   std::unique_ptr<policy::DeviceCloudPolicyValidator> validator =
       policy::DeviceCloudPolicyValidator::Create(std::move(policy),