Remove unneeded functions in web_app.cc.

Remove unneeded functions in web_app.cc.

The main change here is that web_app::GetWebAppDataDirectory
is now being called on the UI thread.

BUG=356889
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=272422

[calamity, 2014-05-21 08:49:40]

lgtm.

[jackhou1, 2014-05-22 01:50:02]

The CQ bit was checked by jackhou@chromium.org

[commit-bot: I haz the power, 2014-05-22 01:53:43]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jackhou@chromium.org/286933012/1

[commit-bot: I haz the power, 2014-05-22 11:52:18]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  win_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu_triggered...)

[commit-bot: I haz the power, 2014-05-22 11:54:35]

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

[commit-bot: I haz the power, 2014-05-22 11:54:36]

Try jobs failed on following builders:
  win_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu_triggered...)

[jackhou1, 2014-05-23 03:17:54]

The CQ bit was checked by jackhou@chromium.org

[commit-bot: I haz the power, 2014-05-23 03:19:49]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jackhou@chromium.org/286933012/1

[commit-bot: I haz the power, 2014-05-23 07:07:22]

Change committed as 272422