Use device Robot Account to access Cloud Print.

chrome/browser/resources/print_preview/data/user_info.js

Index: chrome/browser/resources/print_preview/data/user_info.js
diff --git a/chrome/browser/resources/print_preview/data/user_info.js b/chrome/browser/resources/print_preview/data/user_info.js
index 9d6788d13f6e2beb7a57949efc11237a28bb18c7..eb25615585fc9fb40b92cb0f4ca5d65c0b6cd7cc 100644
--- a/chrome/browser/resources/print_preview/data/user_info.js
+++ b/chrome/browser/resources/print_preview/data/user_info.js
@@ -72,8 +72,10 @@ cr.define('print_preview', function() {
      * @private
      */
     onCloudPrintSearchDone_: function(event) {
-      this.userEmail_ = event.email;
-      cr.dispatchSimpleEvent(this, UserInfo.EventType.EMAIL_CHANGE);
+      if (event.origin == print_preview.Destination.Origin.COOKIES) {
+        this.userEmail_ = event.email;
+        cr.dispatchSimpleEvent(this, UserInfo.EventType.EMAIL_CHANGE);
+      }
     }
   };