Bug 1148862 - Update pref to the new v3 endpoint [r=adw]

browser/app/profile/firefox.js

@@ -1646,10 +1646,10 @@ pref("browser.newtabpage.rows", 3);
 pref("browser.newtabpage.columns", 5);
 
 // directory tiles download URL
-pref("browser.newtabpage.directory.source", "https://tiles.services.mozilla.com/v2/links/fetch/%LOCALE%");
+pref("browser.newtabpage.directory.source", "https://tiles.services.mozilla.com/v3/links/fetch/%LOCALE%/%CHANNEL%");
 
 // endpoint to send newtab click and view pings
-pref("browser.newtabpage.directory.ping", "https://tiles.services.mozilla.com/v2/links/");
+pref("browser.newtabpage.directory.ping", "https://tiles.services.mozilla.com/v3/links/");
 
 // Enable the DOM fullscreen API.
 pref("full-screen-api.enabled", true);