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- Replace SigninErrorController with the errors wrapped by SyncService
- Call opt ins for transport only data
- Rely on SyncService state change for delegate callbacks
- Introduce some new userInfo keys in the NSError object
- Redo unit test to use more fakes

Change-Id: Ibb954e142c254627380658dc9af1e624b96edf98
Bug: 1056416
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2103555
Commit-Queue: John Wu <jzw@chromium.org>
Reviewed-by: Hiroshi Ichikawa <ichikawa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#759132}