Adds TimeDomains to the TaskQueueManager

This refactor isolates the logic dealing with delayed tasks,
making it easier to support multiple independent virtual
time sources.

BUG=546953

Committed: https://crrev.com/fc164806bdf051e28d9160f6854b1782fddc5776
Cr-Commit-Position: refs/heads/master@{#360641}

Review URL: https://codereview.chromium.org/1432263002

Cr-Commit-Position: refs/heads/master@{#360802}
25 files changed