Don't touch the pasteboard when the browser may be shutting down (bookmark model being deleted).
Don't touch the pasteboard when the browser may be shutting down
(bookmark model being deleted).

BUG=38665


Review URL: http://codereview.chromium.org/1165001

git-svn-id: http://src.chromium.org/svn/trunk/src@42249 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: c333e6351805967e2475bec259b166e844c263ef
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