Revert of Enable 'First-Party-Only' cookies by default.

Revert of Enable 'First-Party-Only' cookies by default. (patchset #3 id:40001 of https://codereview.chromium.org/1032063002/)

Reason for revert:
Blink OWNERs would like to wait a bit before shipping: https://groups.google.com/a/chromium.org/d/msg/blink-dev/wKZBCzcNssg/nZ1CFmgddJcJ

Original issue's description:
> Enable 'First-Party-Only' cookies by default.
>
> This patch reverts https://codereview.chromium.org/940373002, and adds
> back in the ~2 lines and tests that are still relevant.
>
> BUG=459154
>
> Committed: https://crrev.com/bdd0b09b5371066ad6d6c0ef2c32f5b92595316d
> Cr-Commit-Position: refs/heads/master@{#322533}

TBR=cbentzel@chromium.org,jochen@chromium.org,rsleevi@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=459154
Committed: https://crrev.com/0513c9d42fe0220d30174c55367e4a13b36f9cfd
Cr-Commit-Position: refs/heads/master@{#323190}

[Mike West, 2015-04-01 05:52:11]

Created Revert of Enable 'First-Party-Only' cookies by default.

[commit-bot: I haz the power, 2015-04-01 05:52:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1043403003/1

[commit-bot: I haz the power, 2015-04-01 05:53:27]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-01 05:54:08]

Patchset 1 (id:??) landed as
https://crrev.com/0513c9d42fe0220d30174c55367e4a13b36f9cfd
Cr-Commit-Position: refs/heads/master@{#323190}