Don't send tab switching/killing/creating keyboard accelerators to pages.  This avoids tabs maliciously preventing closing using ctrl+f4/ctrl+w/alt+f4, and also hung/slow renderers from making tab cycling sluggish.

BUG=5496
TEST=added ui test
Review URL: http://codereview.chromium.org/224023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@27814 0039d316-1c4b-4281-b951-d872f2087c98
25 files changed