gistfile1.js

(function () {
    dl=document.links;

    if(document.location.host!="docs.google.com"){
        for(i=0;i<dl.length;++i){
            if(dl[i].host!="docs.google.com"){
                var ext = dl[i].href.substr(-4);
                if(ext==".pdf"||ext==".ppt"){
                    dl[i].href="http://docs.google.com/viewer?url="+dl[i].href;
                }
            }
        }
    }
})();