Use TaskScheduler instead of SequencedWorkerPool in browser_process_impl.cc.

SequencedWorkerPool is being deprecated in favor of TaskScheduler.

BUG=667892
R=jochen@chromium.org

Review-Url: https://codereview.chromium.org/2881833002
Cr-Commit-Position: refs/heads/master@{#472081}
1 file changed