Introduce a navigator_content_utils module to watchlist, and, add myself to it as a watcher.

BUG=N/A

Review URL: https://codereview.chromium.org/131103006

git-svn-id: svn://svn.chromium.org/blink/trunk@165699 bbb929c8-8fbe-4397-9dbb-9b2b20218538