Adds ui_test_utils::SendAndWaitForKeyPress and converts callers (where

appropriate) to use it. Hopefully this will help isolate why tests are
failing on bot.

BUG=none
TEST=none; test only change.

Review URL: http://codereview.chromium.org/3117030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@57064 0039d316-1c4b-4281-b951-d872f2087c98