Sync: Use SequencedTaskRunner instead of SingleThreadTaskRunner

In ProfileSyncComponentsFactoryImpl, ChromeSyncClient, and the
Autofill DataTypeControllers.

Bug: none
Change-Id: Icd07849f6317451a2303208a8603a214fc3e2c6f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1530914
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Auto-Submit: Marc Treib <treib@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#642925}
8 files changed