Use TaskScheduler instead of blocking pool in supervised_user_site_list.cc.

The blocking pool is being deprecated in favor of TaskScheduler.

BUG=667892
R=bauerb@chromium.org

Review-Url: https://codereview.chromium.org/2841643003
Cr-Commit-Position: refs/heads/master@{#467643}

chrome/browser/supervised_user/supervised_user_site_list.cc

@@ -11,10 +11,8 @@
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
-#include "base/task_runner_util.h"
-#include "base/threading/sequenced_worker_pool.h"
+#include "base/task_scheduler/post_task.h"
 #include "base/values.h"
-#include "content/public/browser/browser_thread.h"
 #include "url/gurl.h"
 
 const int kLegacyWhitelistFormatVersion = 2;
@@ -91,14 +89,16 @@ void SupervisedUserSiteList::Load(const std::string& id,
                                   const base::FilePath& large_icon_path,
                                   const base::FilePath& path,
                                   const LoadedCallback& callback) {
-  base::PostTaskAndReplyWithResult(
-      content::BrowserThread::GetBlockingPool()
-          ->GetTaskRunnerWithShutdownBehavior(
-              base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN)
-          .get(),
-      FROM_HERE, base::Bind(&ReadFileOnBlockingThread, path),
-      base::Bind(&SupervisedUserSiteList::OnJsonLoaded, id, title,
-                 large_icon_path, path, base::TimeTicks::Now(), callback));
+  base::PostTaskWithTraitsAndReplyWithResult(
+      FROM_HERE,
+      base::TaskTraits()
+          .MayBlock()
+          .WithPriority(base::TaskPriority::BACKGROUND)
+          .WithShutdownBehavior(
+              base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN),
+      base::BindOnce(&ReadFileOnBlockingThread, path),
+      base::BindOnce(&SupervisedUserSiteList::OnJsonLoaded, id, title,
+                     large_icon_path, path, base::TimeTicks::Now(), callback));
 }
 
 SupervisedUserSiteList::SupervisedUserSiteList(