Fix accessibility_unittests.

BUG=343580
TBR=avi@chromium.org

Review URL: https://codereview.chromium.org/163233005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251224 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251224