In single-process mode, WebKit isn't yet initialized before we start a renderer,
so we can't pass around WebURLs
BUG=111316
TEST=content_shell --dump-render-tree --single-process doesn't crash
Review URL: https://codereview.chromium.org/11151007
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@161839 0039d316-1c4b-4281-b951-d872f2087c98