Initial checkin of the HTML downloads UI. It's not yet complete (lacking interface polish). But is enough for us to begin removing the native UI.ojan, please review downloads.htmlpaul, please review everything else

      Review URL: http://codereview.chromium.org/20110

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@10050 0039d316-1c4b-4281-b951-d872f2087c98