Add new interactive ui test of spoken feedback.

This is probably too brittle, but I think that's okay at first. As we
add more tests, we should ensure that they don't fail when people make
ordinary, safe changes to the browser.

BUG=none

Review URL: https://codereview.chromium.org/129593003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244482 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244482