Prevent chrome from launching with a chromehtml: argument

      unless its preceeded by the switch terminator.  This is to
prevent chromehtml: urls to supply arguments to Chrome.

BUG=5825

Review URL: http://codereview.chromium.org/20469

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@10684 0039d316-1c4b-4281-b951-d872f2087c98