GTK: Add "Show as Tab" to popup windows.
GTK: Add "Show as Tab" to popup windows.

BUG=44004
TEST=none

Review URL: http://codereview.chromium.org/2099007

git-svn-id: http://src.chromium.org/svn/trunk/src@47683 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 2c605a23cabebdd63dae554781e95f7af7fb5998
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