Use TaskScheduler instead of SequencedWorkerPool in session_manager_operation.cc.

SequencedWorkerPool is being deprecated in favor of TaskScheduler.

Already reviewed on Gerrit: https://codereview.chromium.org/2875393002/

TBR=bartfab@chromium.org

Bug: 667892
Change-Id: I1e89eac5f3464f0f939494f7fff14510f51f1030
Reviewed-on: https://chromium-review.googlesource.com/595874
Commit-Queue: Francois Doray <fdoray@chromium.org>
Reviewed-by: Francois Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490999}
1 file changed