Adding a new folder/url to the BMB via right-click insert it at the location clicked

      BUG=82610


Review URL: https://chromiumcodereview.appspot.com/11567003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@173431 0039d316-1c4b-4281-b951-d872f2087c98