Revert of Disable platform-mode to try and green up tests.

Revert of Disable platform-mode to try and green up tests. (patchset #1 id:1 of https://codereview.chromium.org/1445503002/ )

Reason for revert:
didn't seem to help https://build.chromium.org/p/chromium.swarm/builders/Android%20Swarm/builds/3775

Original issue's description:
> Disable platform-mode to try and green up tests.
>
> BUG=525873
> R=jbudorick@chromium.org
> TBR=jbudorick@chromium.org
> NOTRY=True
> CC=maruel@chromium.org
>
> Committed: https://crrev.com/49b3d93eac886e0fe953b2a3db12c96d99e6ee9e
> Cr-Commit-Position: refs/heads/master@{#359522}

TBR=jbudorick@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=525873
Committed: https://crrev.com/dee5163a66d0842b1aea4da2d97c66b7afd4e73c
Cr-Commit-Position: refs/heads/master@{#359530}

[ghost stip (do not use), 2015-11-13 10:32:07]

Created Revert of Disable platform-mode to try and green up tests.

[commit-bot: I haz the power, 2015-11-13 10:32:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1445523002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1445523002/1

[commit-bot: I haz the power, 2015-11-13 10:33:02]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-13 10:33:59]

Patchset 1 (id:??) landed as
https://crrev.com/dee5163a66d0842b1aea4da2d97c66b7afd4e73c
Cr-Commit-Position: refs/heads/master@{#359530}