cros: Fixed 3 bugs for pin unlock.

ui/login/account_picker/screen_account_picker.js

 // Copyright 2014 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 Account picker screen implementation.
  */
 
 login.createScreen('AccountPickerScreen', 'account-picker', function() {
   /**
@@ skipping 198 matching lines @@
                                               error,
                                               BUBBLE_OFFSET, BUBBLE_PADDING);
           };
           activatedPod.addEventListener("webkitTransitionEnd", showTopCallback);
           ensureTransitionEndEvent(activatedPod);
         }
       }
     },
 
     /**
-     * Loads the PIN keyboard if any of the users can login with a PIN.
+     * Loads the PIN keyboard if any of the users can login with a PIN. Disables
+     * the PIN keyboard for users who are not allowed to use PIN unlock.
      * @param {array} users Array of user instances.
      */
-    loadPinKeyboardIfNeeded_: function(users) {
+    initializePinKeyboardStateForUsers_: function(users) {
       for (var i = 0; i < users.length; ++i) {
         var user = users[i];
         if (user.showPin) {
           showPinKeyboardAsync();
-          return;
+        } else {
+          // Disable pin for users who cannot authenticate with PIN. For
+          // example, users who have not set up PIN or users who have not
+          // entered their account recently. Otherwise, the PIN keyboard will
+          // will appear for any user if there is at least one user who has PIN
+          // enabled.
+          this.disablePinKeyboardForUser(user.username);
         }
       }
     },
 
     /**
      * Loads given users in pod row.
      * @param {array} users Array of user.
      * @param {boolean} showGuest Whether to show guest session button.
      */
     loadUsers: function(users, showGuest) {
       $('pod-row').loadPods(users);
       $('login-header-bar').showGuestButton = showGuest;
       // On Desktop, #login-header-bar has a shadow if there are 8+ profiles.
       if (Oobe.getInstance().displayType == DISPLAY_TYPE.DESKTOP_USER_MANAGER)
         $('login-header-bar').classList.toggle('shadow', users.length > 8);
 
-      this.loadPinKeyboardIfNeeded_(users);
+      this.initializePinKeyboardStateForUsers_(users);
     },
 
     /**
      * Runs app with a given id from the list of loaded apps.
      * @param {!string} app_id of an app to run.
      * @param {boolean=} opt_diagnostic_mode Whether to run the app in
      *     diagnostic mode.  Default is false.
      */
     runAppForTesting: function(app_id, opt_diagnostic_mode) {
       $('pod-row').findAndRunAppForTesting(app_id, opt_diagnostic_mode);
@@ skipping 158 matching lines @@
      * @param {string} userID The user ID of the public session
      * @param {string} locale The locale to which this list of keyboard layouts
      *     applies
      * @param {!Object} list List of available keyboard layouts
      */
     setPublicSessionKeyboardLayouts: function(userID, locale, list) {
       $('pod-row').setPublicSessionKeyboardLayouts(userID, locale, list);
     }
   };
 });