Fix JS errors of FileTransferController.

Fix JS errors of FileTransferController.

Previously Files.app does not preapre container object of AsyncData if the
selection includes directory. Thus it raises exceptions when it tries to
store data to the container object. The CL let Files.app prepares the container
object always.

BUG=461726
TEST=None

Committed: https://crrev.com/42e39712923bd4ae01458124e9183492adb099a6
Cr-Commit-Position: refs/heads/master@{#318187}

[hirono, 2015-02-26 02:16:40]

hirono@chromium.org changed reviewers:
+ mtomasz@chromium.org

[hirono, 2015-02-26 02:16:40]

PTAL, thanks!

[mtomasz, 2015-02-26 04:12:31]

Thanks! lgtm!

[hirono, 2015-02-26 04:37:36]

The CQ bit was checked by hirono@chromium.org

[hirono, 2015-02-26 04:37:42]

On 2015/02/26 04:12:31, mtomasz wrote:
> Thanks! lgtm!

Thanks!

[commit-bot: I haz the power, 2015-02-26 04:38:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/956853002/1

[commit-bot: I haz the power, 2015-02-26 04:47:58]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-26 04:48:48]

Patchset 1 (id:??) landed as
https://crrev.com/42e39712923bd4ae01458124e9183492adb099a6
Cr-Commit-Position: refs/heads/master@{#318187}