Back button for the WebView-based sign-in flow.

Back button for the WebView-based sign-in flow.

The button state is being updated in the backButton event.
It remains hidden until the first such event and after each
click, so the <webview> can always control if the button is
needed at all.

BUG=462660
Committed: https://crrev.com/46217629a68853bc7d3a21b65180fe6c71d39f5f
Cr-Commit-Position: refs/heads/master@{#321990}

[Ivan Podogov, 2015-03-23 14:37:23]

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

[Ivan Podogov, 2015-03-23 14:37:33]

PTAL

[oshima, 2015-03-23 21:01:00]

c/a/theme lgtm

[Nikita (slow), 2015-03-24 11:56:03]

lgtm

please update CL description

https://codereview.chromium.org/1029053002/diff/40001/chrome/browser/resource...
File chrome/browser/resources/chromeos/login/screen_gaia_signin.html (right):

https://codereview.chromium.org/1029053002/diff/40001/chrome/browser/resource...
chrome/browser/resources/chromeos/login/screen_gaia_signin.html:40:
i18n-values="aria-label:backButton" tabindex="0"></button>
nit: just 4 spaces indent for attributes

https://codereview.chromium.org/1029053002/diff/40001/chrome/browser/resource...
chrome/browser/resources/chromeos/login/screen_gaia_signin.html:42:
i18n-values="aria-label:closeButton" tabindex="0"></button>
nit: same here

[Ivan Podogov, 2015-03-24 12:49:37]

The CQ bit was checked by ginkage@chromium.org

[Ivan Podogov, 2015-03-24 12:49:37]

The patchset sent to the CQ was uploaded after l-g-t-m from oshima@chromium.org,
nkostylev@chromium.org
Link to the patchset: https://codereview.chromium.org/1029053002/#ps60001
(title: "Nit.")

[commit-bot: I haz the power, 2015-03-24 12:50:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1029053002/60001

[commit-bot: I haz the power, 2015-03-24 13:30:13]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-03-24 13:31:01]

Patchset 4 (id:??) landed as
https://crrev.com/46217629a68853bc7d3a21b65180fe6c71d39f5f
Cr-Commit-Position: refs/heads/master@{#321990}