Switch GAIA e-mail address retrieval from /GetUserInfo to /ListAccounts

Switch GAIA e-mail address retrieval from /GetUserInfo to /ListAccounts

Previously, the Chrome OS SAML login flow was passing the LSID obtained
via /ServiceLogin to /GetUserInfo in order to retrieve the authenticated
user's e-mail address. It turns out that this is wrong because
/ServiceLogin yields a browser LSID and /GetUserInfo expects a
programmatic LSID. In many cases, the two LSID flavors are identical and
the existing code worked. But under some conditions, the browser LSID
could be different, causing /GetUserInfo to fail.

This CL switches to /ListAccounts instead, which handles browser LSIDs.
An additional advantage of /ListAccounts is that it will read the LSID
from cookies, removing the need to extract the LSID from the cookie jar
explicitly.

I could have further simplified the code by doing an XHR to /ListAccounts
from the JS code of the auth extension, avoiding the JS -> C++ -> JS round
trip. However, this would have been a CORS request, requiring the GAIA
URL to be hard-coded in the auth extension's manifest. The implementation
in this CL, which makes the /ListAccounts call from C++, is more flexible
as it preserves the ability to change the GAIA URL via a command-line
flag.

BUG=332132
TEST=Updated browser test and manual

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=245585

[bartfab (slow), 2014-01-17 13:43:42]

Hi Xiyuan,

Could you please review authenticated_user_email_retriever.*?

Hi Zel,

Could you please review fake_gaia.*?

[zel, 2014-01-17 15:52:34]

lgtm

[xiyuan, 2014-01-17 17:15:35]

LGTM

Good findings and I learned something today. :)

[commit-bot: I haz the power, 2014-01-17 17:30:35]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/bartfab@chromium.org/134483008/1

[commit-bot: I haz the power, 2014-01-17 19:35:32]

Change committed as 245585