Fix for invocation over deprecated protocol handler

      - We don't support chromehtml protocol anymore and future installers do not register it
- Avoid stale registry entries to invoke us

BUG=9860
BUG=9862


Review URL: http://codereview.chromium.org/64003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@13384 0039d316-1c4b-4281-b951-d872f2087c98