Hide the exit bubble when the main window is inactivated, and don't re-show until it's reactivated.
Hide the exit bubble when the main window is inactivated, and don't re-show until it's reactivated.

BUG=8945
Review URL: http://codereview.chromium.org/93048

git-svn-id: http://src.chromium.org/svn/trunk/src@14270 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 39f671898780244ab8e4a89753a6bbfa43ed1511
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