Added Signin Utilites (RE-LAND)

Added Signin Utilites (RE-LAND)

Re-Land of https://codereview.chromium.org/1258563005/

- Made Google OS Sign-in Tests FlakyTest
- Fixed test account preferences that caused the real Google account sign-in tests to fail previously.

BUG=

Committed: https://crrev.com/fdfcc1041386b4e8e48c30d3d9463bd84ba5d731
Cr-Commit-Position: refs/heads/master@{#342385}

[Sean Kirmani, 2015-08-07 16:41:42]

skirmani@google.com changed reviewers:
+ jbudorick@chromium.org

[jbudorick, 2015-08-07 17:38:39]

jbudorick@chromium.org changed reviewers:
+ yfriedman@chromium.org

[jbudorick, 2015-08-07 17:38:39]

lgtm

+yfriedman for owners

[Yaron, 2015-08-07 17:42:42]

lgtm
In the future it's helpful to upload the original patch as patchset 1 so that we
can see the difference from previous attempts within the tool

[Sean Kirmani, 2015-08-07 17:43:14]

The CQ bit was checked by skirmani@google.com

[commit-bot: I haz the power, 2015-08-07 17:43:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1279483003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1279483003/1

[commit-bot: I haz the power, 2015-08-07 18:17:44]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-07 18:18:46]

Patchset 1 (id:??) landed as
https://crrev.com/fdfcc1041386b4e8e48c30d3d9463bd84ba5d731
Cr-Commit-Position: refs/heads/master@{#342385}