Migrate iOS DownloadManagerController to TaskScheduler

R=rohitrao@chromium.org

Bug: 667892
Change-Id: Ia6cd649c678a65a1f16351864d6a88c9a8e4b9d2
Reviewed-on: https://chromium-review.googlesource.com/590080
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490770}
1 file changed