Add close button to the supervised user pages.

chrome/browser/resources/chromeos/login/screen_supervised_user_creation.js

Index: chrome/browser/resources/chromeos/login/screen_supervised_user_creation.js
diff --git a/chrome/browser/resources/chromeos/login/screen_supervised_user_creation.js b/chrome/browser/resources/chromeos/login/screen_supervised_user_creation.js
index be8f355afb8977c9f6ee17db776ad3c0c3f183d5..c7d44f88d90d3112820845fe1a02f7995bd004ca 100644
--- a/chrome/browser/resources/chromeos/login/screen_supervised_user_creation.js
+++ b/chrome/browser/resources/chromeos/login/screen_supervised_user_creation.js
@@ -616,6 +616,12 @@ login.createScreen('SupervisedUserCreationScreen',
           'webkitTransitionEnd', function(e) {
             previewElement.classList.remove('animation');
           });
+
+      $('supervised-user-creation-close-button-item').addEventListener(
+          'click', function(e) {
+            this.cancel();
+            e.preventDefault();
+          }.bind(this));
     },
 
     buttonIds: [],
@@ -1193,6 +1199,9 @@ login.createScreen('SupervisedUserCreationScreen',
             !this.importList_.selectedPod_ ||
             this.importList_.selectedPod_.user.exists;
       }
+      $('supervised-user-creation-close-button-item').hidden =
+          (visiblePage == 'created');
+
       chrome.send('currentSupervisedUserPage', [this.currentPage_]);
     },