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: de016e52bd170d2d4f2344f9bf92d50478b649e0@19301 0039d316-1c4b-4281-b951-d872f2087c98

ropik/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,adobe/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,ropik/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,ropik/chromium,yitian134/chromium,adobe/chromium,yitian134/chromium