gtk: Post the SendNotification in a task on the UI thread.  In rare instances, SendNotifications was being run before CancelAuthDeferred, so the proper cleanup was not happening before this object was deleted which leads to a crash.
gtk: Post the SendNotification in a task on the UI thread.  In rare instances, SendNotifications was being run before CancelAuthDeferred, so the proper cleanup was not happening before this object was deleted which leads to a crash.

BUG=18973
TEST=Instructions in the bug report.
Review URL: http://codereview.chromium.org/165268

git-svn-id: http://src.chromium.org/svn/trunk/src@22984 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 6adaeeb5f554f2586fa667599dd9965d7ad359e7
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