[chromedriver] Fix python tests.

BUG=
NOTRY=True

Review URL: https://codereview.chromium.org/131563004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245584 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245584
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

Review URL: https://codereview.chromium.org/134483008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245585 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245585