GitLab

This will improve feedback for a couple of toolbar controls that check
this state, and also start collecting UMA statistics on accessibility usage
in Chrome OS.

BUG=99504
TEST=none

Review URL: http://codereview.chromium.org/8537024

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@109851 0039d316-1c4b-4281-b951-d872f2087c98