NNTP: Make sure that the window tooltip is within the browser viewport.
NNTP: Make sure that the window tooltip is within the browser viewport.

BUG=18534

TEST=Open a new window. Open several tabs in this window and then close
the window. An item representing this window should be shown on the new
tab page. Hover this item (or tab to it). The tooltip should be
repositioned so that it is not clipped by the window viewport.


Review URL: http://codereview.chromium.org/173100

git-svn-id: http://src.chromium.org/svn/trunk/src@23825 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 401989d34a8c5d6e34ee5b10d7c709e9c49d543c
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