Pausable Workers - Remove usage of kInternalWorker for Timezone change

Switching the timezone can be a pausable activity so switch the task
type to be kInternalDefault which is pausable.

BUG=907125

Change-Id: I9f8e069b580355d32c2839e981d4494a034d0e6c
Reviewed-on: https://chromium-review.googlesource.com/c/1387126
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#620705}
2 files changed