Linux: add Alt-n keys for switching tabs.
Linux: add Alt-n keys for switching tabs.

The UI decision was to have both Alt-n and Ctrl-n switch tabs. Ctrl-n
to match Windows Chrome and Alt-n to match Firefox on Linux. Pages
which try to grab either sets of keys will succeed.

BUG=13395


git-svn-id: http://src.chromium.org/svn/trunk/src@19301 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 49efaf275bc68bbeaae7a9e853f215e747bdb62f
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