cros: Fixed 3 bugs for pin unlock.

ui/login/account_picker/screen_account_picker.js

Index: ui/login/account_picker/screen_account_picker.js
diff --git a/ui/login/account_picker/screen_account_picker.js b/ui/login/account_picker/screen_account_picker.js
index 69c5eafe3dbb55e5b6523da09c79a181a2be8fd0..c2cf478d66885cca1909f0a7713d1868e7a9c3f0 100644
--- a/ui/login/account_picker/screen_account_picker.js
+++ b/ui/login/account_picker/screen_account_picker.js
@@ -224,15 +224,20 @@ login.createScreen('AccountPickerScreen', 'account-picker', function() {
     },
 
     /**
-     * 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 allowed to use PIN unlock.

[jdufault, 2016/10/19 22:13:25]

nit: who are not*

[sammiequon, 2016/10/20 16:50:00]

Done.

      * @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();

[jdufault, 2016/10/19 22:13:25]

I wonder if calling this multiple times will cause a problem / performance
slowdown. I know the comment on the function says it won't, but I think the
implementation is slightly wrong. Can you change showPinKeyboardAsync so that it
calls

  cr.ui.login.ResourceLoader.hasDeferredAssets

instead of

  cr.ui.login.ResourceLoader.alreadyLoadedAssets

[sammiequon, 2016/10/20 16:50:00]

Done.

-          return;
+        } else {
+          // Disable pin for users which should not be able to access pin. Such
+          // users include those who have not set up pin as those who have not
+          // entered their password recently.
+          this.disablePinKeyboardForUser(user.username);
         }
       }
     },
@@ -249,7 +254,7 @@ login.createScreen('AccountPickerScreen', 'account-picker', function() {
       if (Oobe.getInstance().displayType == DISPLAY_TYPE.DESKTOP_USER_MANAGER)
         $('login-header-bar').classList.toggle('shadow', users.length > 8);
 
-      this.loadPinKeyboardIfNeeded_(users);
+      this.initializePinKeyboardStateForUsers_(users);
     },
 
     /**