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

chrome/browser/resources/md_user_manager/profile_browser_proxy.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview Helper object and related behavior that encapsulate messaging
  * between JS and C++ for creating/importing profiles in the user-manager page.
  */
 
 /** @typedef {{username: string, profilePath: string}} */
@@ skipping 100 matching lines @@
     openUrlInLastActiveProfileBrowser: function(url) {
       assertNotReached();
     },
 
     /**
      * Switches to the profile with the given path.
      * @param {string} profilePath Path to the profile to switch to.
      */
     switchToProfile: function(profilePath) {
       assertNotReached();
+    },
+
+    /**
+     * Returns a Promise that is resolved if at least one (non-supervised and
+     * non-child) profile is unlocked, and is rejected otherwise.
+     * @return {Promise}
+     */
+    isAtLeastOneProfileUnlocked: function() {
+      assertNotReached();
     }
   };
 
   /**
    * @constructor
    * @implements {signin.ProfileBrowserProxy}
    */
   function ProfileBrowserProxyImpl() {}
 
   // The singleton instance_ is replaced with a test version of this wrapper
@@ skipping 45 matching lines @@
     },
 
     /** @override */
     openUrlInLastActiveProfileBrowser: function(url) {
       chrome.send('openUrlInLastActiveProfileBrowser', [url]);
     },
 
     /** @override */
     switchToProfile: function(profilePath) {
       chrome.send('switchToProfile', [profilePath]);
+    },
+
+    /** @override */
+    isAtLeastOneProfileUnlocked: function() {
+      return cr.sendWithPromise('isAtLeastOneProfileUnlocked');
     }
   };
 
   return {
     ProfileBrowserProxy: ProfileBrowserProxy,
     ProfileBrowserProxyImpl: ProfileBrowserProxyImpl,
   };
 });