Add unit test for the back button in the new GAIA.

Add unit test for the back button in the new GAIA.

BUG=475566
Committed: https://crrev.com/069e1f8c090a54cc71d5dc0b4ec4dfb5012c647e
Cr-Commit-Position: refs/heads/master@{#325206}

[Ivan Podogov, 2015-04-14 15:09:27]

ginkage@chromium.org changed reviewers:
+ nkostylev@chromium.org, rogerta@chromium.org

[Ivan Podogov, 2015-04-14 15:13:09]

PTAL

[Roger Tawa OOO till Jul 10th, 2015-04-14 18:55:16]

google_apis lgtm

[Nikita (slow), 2015-04-14 20:06:13]

lgtm

https://codereview.chromium.org/1057393004/diff/40001/google_apis/test/embedd...
File google_apis/test/embedded_setup_chromeos.html (right):

https://codereview.chromium.org/1057393004/diff/40001/google_apis/test/embedd...
google_apis/test/embedded_setup_chromeos.html:57: history.replaceState({}, "",
window.location.pathname + "#identifier");
nit: Use ' instead of "
Here and below

[Ivan Podogov, 2015-04-15 07:23:05]

The CQ bit was checked by ginkage@chromium.org

[Ivan Podogov, 2015-04-15 07:23:05]

The patchset sent to the CQ was uploaded after l-g-t-m from
nkostylev@chromium.org, rogerta@chromium.org
Link to the patchset: https://codereview.chromium.org/1057393004/#ps60001
(title: "Nit.")

[commit-bot: I haz the power, 2015-04-15 07:23:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1057393004/60001

[commit-bot: I haz the power, 2015-04-15 07:53:44]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-04-15 07:54:41]

Patchset 4 (id:??) landed as
https://crrev.com/069e1f8c090a54cc71d5dc0b4ec4dfb5012c647e
Cr-Commit-Position: refs/heads/master@{#325206}