Implement ErrorScreenHandler::Hide method

Implement ErrorScreenHandler::Hide method

Also make sure that default hide callback does nothing
if parent screen was not set.

Follow up to a refactoring
https://codereview.chromium.org/872633008/

BUG=462453
TEST=manually, existing browser tests

Committed: https://crrev.com/ddb237aaffbd04829c285d994089092ef128d6fb
Cr-Commit-Position: refs/heads/master@{#319282}

[Nikita (slow), 2015-03-05 17:28:59]

nkostylev@chromium.org changed reviewers:
+ antrim@chromium.org

[Nikita (slow), 2015-03-05 17:29:00]

Based on https://codereview.chromium.org/978213002/
just fixed tests which discovered another bug.

[Denis Kuznetsov (DE-MUC), 2015-03-05 17:35:01]

lgtm

[Denis Kuznetsov (DE-MUC), 2015-03-05 17:36:23]

The CQ bit was checked by antrim@chromium.org

[commit-bot: I haz the power, 2015-03-05 17:37:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/982823004/1

[commit-bot: I haz the power, 2015-03-05 18:03:35]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-05 18:05:33]

Patchset 1 (id:??) landed as
https://crrev.com/ddb237aaffbd04829c285d994089092ef128d6fb
Cr-Commit-Position: refs/heads/master@{#319282}