ng-href에서 item-service 프로토콜을 unsafe라는 prefix가 추가가 되어서 해결책을 찾아보았다.
<a href="unsafe:item-service:...">...</a>
/**
* @description
* Private service to sanitize uris for links and images. Used by $compile and $sanitize.
*/
function $$SanitizeUriProvider() {
var aHrefSanitizationWhitelist = /^\s*(https?|ftp|mailto|tel|file):/,
imgSrcSanitizationWhitelist = /^\s*(https?|ftp|file):|data:image\//;
...
app.config(['$compileProvider', function($compileProvider){
$compileProvider.aHrefSanitizationWhitelist(/^\s*(https?|ftp|mailto|tel|file|itms-services):/);
...
http://stackoverflow.com/questions/15606751/angular-changes-urls-to-unsafe-in-extension-page