Enable new sign in flow for E2E tests.

Enable new sign in flow for E2E tests.

There are multiple possible login pages based on the Gaia server version
we hit in the E2E tests.

This change should not affect existing tests on the waterfall.

BUG=477157
Committed: https://crrev.com/102fd46d29c2a3b0b17fccb574af1027865cd13d
Cr-Commit-Position: refs/heads/master@{#327133}

[shadi, 2015-04-22 21:19:08]

shadi@chromium.org changed reviewers:
+ rogerta@chromium.org

[Roger Tawa OOO till Jul 10th, 2015-04-23 14:32:33]

lgtm

[shadi, 2015-04-23 18:17:11]

Thanks Roger for quick reply. I have been looking into content::ExecuteScript*
functions and noticed we are mis-using it. 

PTAL on the changes done.

https://codereview.chromium.org/1102603003/diff/20001/chrome/browser/ui/webui...
File chrome/browser/ui/webui/signin/login_ui_test_utils.cc (right):

https://codereview.chromium.org/1102603003/diff/20001/chrome/browser/ui/webui...
chrome/browser/ui/webui/signin/login_ui_test_utils.cc:88:
ASSERT_TRUE(content::ExecuteScript(
ExecuteScript is a bad use here since it already adds a
domAutomationController.send(0) to the default script:
https://code.google.com/p/chromium/codesearch#chromium/src/content/public/tes...

https://codereview.chromium.org/1102603003/diff/20001/chrome/browser/ui/webui...
chrome/browser/ui/webui/signin/login_ui_test_utils.cc:103:
ASSERT_TRUE(message_queue.WaitForMessage(&message));
Using ExecuteScriptAndExtractString should return only one message back and make
this more stable here and below.

[Roger Tawa OOO till Jul 10th, 2015-04-23 18:28:48]

still lgtm

Very nice catch Shadi!

[shadi, 2015-04-27 20:54:34]

The CQ bit was checked by shadi@chromium.org

[commit-bot: I haz the power, 2015-04-27 20:56:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1102603003/40001

[commit-bot: I haz the power, 2015-04-27 21:34:58]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-04-27 21:35:49]

Patchset 3 (id:??) landed as
https://crrev.com/102fd46d29c2a3b0b17fccb574af1027865cd13d
Cr-Commit-Position: refs/heads/master@{#327133}