Re-apply 17223 (http://codereview.chromium.org/115943) to fix external tab handling of certain open dispositions.
Re-apply 17223 (http://codereview.chromium.org/115943) to fix external tab handling of certain open dispositions.

Review URL: http://codereview.chromium.org/118030

git-svn-id: http://src.chromium.org/svn/trunk/src@17315 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 056f38ce744d7f7fd9879ccc3de36866ed133bcf
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