Fix GTK version of options dialog to place it to the center of last active browser window.
Fix GTK version of options dialog to place it to the center of last active browser window.

BUG=1143
TEST=Tested on Linux with two monitors.

Review URL: http://codereview.chromium.org/551094

git-svn-id: http://src.chromium.org/svn/trunk/src@37135 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: e17b73b373a445f489b0aacec6d764fab1233422
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser