com.sap.wrr is the 'Resources provided by SAP' folder..
I can access the url - http://host:port/com.sap.portal.resourcerepository/repo/com.sap.wrr/Mobile/application_icons/favorites-smartphone.png
I tried with a different image but it still did not work - /com.sap.portal.resourcerepository/repo/FFP_DEMO/EPTile_HR_Direct.jpg