[Sync] Some cleanup of SyncTestUtil.

[Sync] Some cleanup of SyncTestUtil.

- Removes the Context argument from places it isn't needed.
- Removes everything related to about://sync as there are now better
  ways to access sync state.
- Have just TIMEOUT_MS and INTERVAL_MS.
- Some other misc cleanups.

BUG=556621
Committed: https://crrev.com/78b449d801f2b1155c0a6aa2175cdea5f0f77a93
Cr-Commit-Position: refs/heads/master@{#360586}

[maxbogue, 2015-11-18 17:02:55]

maxbogue@chromium.org changed reviewers:
+ pvalenzuela@chromium.org

[maxbogue, 2015-11-18 17:02:55]

Hey Patrick, PTAL! This is at least a start for cleaning up SyncTestUtil.

[pval...(no longer on Chromium), 2015-11-18 22:47:16]

lgtm

nice cleanup/improvements

[maxbogue, 2015-11-19 14:51:26]

The CQ bit was checked by maxbogue@chromium.org

[commit-bot: I haz the power, 2015-11-19 14:51:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1451813002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1451813002/1

[commit-bot: I haz the power, 2015-11-19 15:44:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-19 15:46:34]

Patchset 1 (id:??) landed as
https://crrev.com/78b449d801f2b1155c0a6aa2175cdea5f0f77a93
Cr-Commit-Position: refs/heads/master@{#360586}