Fix focus on popup GTK dialogs

Fix focus on popup GTK dialogs

Previously we didn't have a call to gtk_window_present(), which would
mean that the widgets would become visible, but the necessary actions to
focus weren't always taken. This resulted in the active window not being
correct after opening the file or print dialogs.

BUG=399514
Committed: https://crrev.com/b7954eebe6fe06dd1e585c83efa7a20e7be0a2ac
Cr-Commit-Position: refs/heads/master@{#293691}

[Arjan van Leeuwen, 2014-09-05 13:29:16]

arjanl@opera.com changed reviewers:
+ erg@chromium.org

[Elliot Glaysher, 2014-09-05 17:21:47]

lgtm

[Arjan van Leeuwen, 2014-09-08 07:54:01]

The CQ bit was checked by arjanl@opera.com

[commit-bot: I haz the power, 2014-09-08 07:55:13]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/arjanl@opera.com/543093002/1

[commit-bot: I haz the power, 2014-09-08 08:51:50]

Committed patchset #1 (id:1) as d4b45f0ede6a83aa0ba71fe42cc9316b5c87f79a

[commit-bot: I haz the power, 2014-09-10 03:45:15]

Patchset 1 (id:??) landed as
https://crrev.com/b7954eebe6fe06dd1e585c83efa7a20e7be0a2ac
Cr-Commit-Position: refs/heads/master@{#293691}