[CrOS MP] Add --multi-profiles switch in some tests

[CrOS MP] Add --multi-profiles switch in some tests
* ProfileHelperTest
* ExistingUserControllerTest
* ExistingUserControllerPublicSessionTest
* ExtensionNetworkingPrivateApiTest

BUG=230464
NOTRY=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=201306

[Nikita (slow), 2013-05-20 08:49:08]

These are the first tests that will be running for both existing and
multi-profiles setup. I'll be adding more test cases to existing tests and
creating new tests that are targeted to multi-profiles.

[Nikita (slow), 2013-05-20 10:54:38]

cc:pneubeck

[Nikita (slow), 2013-05-21 09:49:35]

Zel need OWNERS lgtm for 
chrome/browser/chromeos/extensions/*

[Nikita (slow), 2013-05-21 09:50:28]

+Dmitry for code review

[pneubeck (no reviews), 2013-05-21 10:33:36]

networking apitest lgtm.

[Dmitry Polukhin, 2013-05-21 10:38:23]

LGTM but please run more trybots for Chrome OS.

[zel, 2013-05-21 14:06:16]

lgtm

https://codereview.chromium.org/15305011/diff/14001/chrome/browser/chromeos/e...
File chrome/browser/chromeos/extensions/networking_private_apitest.cc (right):

https://codereview.chromium.org/15305011/diff/14001/chrome/browser/chromeos/e...
chrome/browser/chromeos/extensions/networking_private_apitest.cc:68: }
nit: no {}

[commit-bot: I haz the power, 2013-05-21 15:09:43]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/nkostylev@chromium.org/15305011/20001

[commit-bot: I haz the power, 2013-05-21 15:13:04]

Change committed as 201306