background.html

<html>
 	<head>
 		<script type="text/javascript" src="multiswitch-core.js"></script>
    	<script type="text/javascript">  	

    	var apps = null;
    	var currentApp = null;
    	var currentHost = null;
    	
    	var init = function(){
    		loadAppList();
       	chrome.tabs.onUpdated.addListener(function(tabId,info,tab) {
					if(info.status=="loading"){
       			getUrl(tab);
					}
       	});
       	chrome.tabs.onSelectionChanged.addListener(function(tabId,info) {
          chrome.tabs.get(tabId,getUrl);
       	});
      };

      var loadAppList = function(){
				apps=MultiSwitch.Apps.list();
      };

      var refresh = function(){
          loadAppList();
      };
    	
     	var getUrl=function(tab) {
        refresh();
     		var url = tab.url;
     		var app = getAppForURL(url);
     		if(app!=null) {
         		currentApp = app;
         		chrome.pageAction.show(tab.id);
     		} else {
        	currentApp=null;
     			chrome.pageAction.hide(tab.id);
     		}
     	};

     	var getAppForURL = function(url) {
       	if(apps!=null)
        {
           	for(var i=0;i<apps.length;i++)
            {
               	var app = apps[i];
               	var hosts=app.hosts();
               	for(var j=0;j<hosts.length;j++)
                {
                   	var host = hosts[j];
                   	if(url.indexOf(host.prefix)>-1)
                    {
                        currentHost = host;
                       	return app;
                   	}
               	}
           	}
       	}
       	return null;
     	};

    	</script>
  	</head>
  	<body onload="init();">
  	</body>
</html>