Build fix: add a stub for background_x11_thread for unit tests
Build fix: add a stub for background_x11_thread for unit tests


git-svn-id: http://src.chromium.org/svn/trunk/src@14078 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 66a2a1bda2c5fb8879d14d960beb81ecf58ea1cb
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