MD User Manager: Display error message when all profiles are locked.

chrome/browser/resources/md_user_manager/control_bar.js

Index: chrome/browser/resources/md_user_manager/control_bar.js
diff --git a/chrome/browser/resources/md_user_manager/control_bar.js b/chrome/browser/resources/md_user_manager/control_bar.js
index 3c2b6362923985860b326cf118c8863693892a23..6bf22cb61c32bea73ccf92f777aefffb341429b9 100644
--- a/chrome/browser/resources/md_user_manager/control_bar.js
+++ b/chrome/browser/resources/md_user_manager/control_bar.js
@@ -9,6 +9,10 @@
  Polymer({
   is: 'control-bar',
 
+  behaviors: [
+    I18nBehavior,
+  ],
+
   properties: {
     /**
      * True if 'Browse as Guest' button is displayed.
@@ -50,9 +54,15 @@
    * Handler for 'Add Person' button click event.
    * @param {!Event} event
    * @private
+   * @suppress {checkTypes}
    */
   onAddUserTap_: function(event) {
-    // Event is caught by user-manager-pages.
-    this.fire('change-page', {page: 'create-user-page'});
+    if (cr.ui.UserManager.getInstance().areAllProfilesLocked) {
+      cr.ui.UserManager.showErrorDialog(
+          this.i18n('AddProfileAllProfilesLockedError'));
+    } else {
+      // Event is caught by user-manager-pages.
+      this.fire('change-page', {page: 'create-user-page'});
+    }
   }
 });