Revert of Make File-Picker modal on Linux

Revert of Make File-Picker modal on Linux (patchset #8 id:140001 of https://codereview.chromium.org/1045443002/)

Reason for revert:
This patch causes DCHECK failure. Refer to:
https://code.google.com/p/chromium/issues/detail?id=510957

Original issue's description:
> Make File-Picker modal on Linux
>
> Chromium for Linux opens a Gtk file-picker for file browsing, but it is not
> modal because there is no GtkWindow as parent of file-picker.
>
> This patch allows the X11 host window to disable input event handling to make
> a file-picker modal.
>
> BUG=408481
>
> Committed: https://crrev.com/b440cbb929e62a238f97590d79bd78333adef7ce
> Cr-Commit-Position: refs/heads/master@{#338870}

BUG=408481, 510957
Committed: https://crrev.com/bae7a498705ae28e2d08567928df640a7d48fa37
Cr-Commit-Position: refs/heads/master@{#339173}

[juncai, 2015-07-16 22:01:10]

Created Revert of Make File-Picker modal on Linux

[juncai, 2015-07-16 22:02:30]

Please review this patch.

[Elliot Glaysher, 2015-07-16 22:08:03]

The CQ bit was checked by erg@chromium.org

[Elliot Glaysher, 2015-07-16 22:08:04]

lgtm

[commit-bot: I haz the power, 2015-07-16 22:08:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1243503002/1

[commit-bot: I haz the power, 2015-07-16 23:51:17]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-16 23:53:17]

Patchset 1 (id:??) landed as
https://crrev.com/bae7a498705ae28e2d08567928df640a7d48fa37
Cr-Commit-Position: refs/heads/master@{#339173}