Fixes to get view_manager_lib_unittests not crash

Fixes to get view_manager_lib_unittests not crash

. ICU may be initialized twice: once by the test suite, secondly by
  the app.
. window_mamanger_app_.host_ may be deleted by the time we get to the
  destructor to try and remove something. Add check for this.

BUG=none
TEST=none
R=viettrungluu@chromium.org

Committed: https://crrev.com/2997d2df654d38113e80612109a8cfcac5098ccf
Cr-Commit-Position: refs/heads/master@{#292929}

[sky, 2014-08-28 17:49:18]

sky@chromium.org changed reviewers:
+ viettrungluu@chromium.org
- jamesr@chromium.org

[viettrungluu, 2014-08-28 19:17:06]

lgtm

[sky, 2014-08-28 19:17:29]

The CQ bit was checked by sky@chromium.org

[commit-bot: I haz the power, 2014-08-28 19:19:14]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sky@chromium.org/516523004/1

[commit-bot: I haz the power, 2014-08-28 20:15:13]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-08-28 20:15:14]

Failed to commit the patch.

[sky, 2014-08-28 20:18:08]

The CQ bit was checked by sky@chromium.org

[commit-bot: I haz the power, 2014-08-28 20:18:53]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sky@chromium.org/516523004/1

[commit-bot: I haz the power, 2014-08-28 20:21:13]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-08-28 20:21:14]

Failed to commit the patch.

[sky, 2014-09-02 15:11:04]

The CQ bit was checked by sky@chromium.org

[commit-bot: I haz the power, 2014-09-02 15:12:00]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sky@chromium.org/516523004/1

[commit-bot: I haz the power, 2014-09-02 15:21:09]

Committed patchset #1 (id:1) as 94e1c03fe0ef5827ad403cf8a7f923710130329f

[commit-bot: I haz the power, 2014-09-10 03:18:35]

Patchset 1 (id:??) landed as
https://crrev.com/2997d2df654d38113e80612109a8cfcac5098ccf
Cr-Commit-Position: refs/heads/master@{#292929}