cros: Fix regression with pin message persistent in confirm stage.

Partial reverted the cl which introduced this regression. I will reopen
the original bug and try a better fix later.

Test: manual
Bug: 881756, 907002
Change-Id: Idbe3a587caad485968d78b0b4841f1bfa0105366
Reviewed-on: https://chromium-review.googlesource.com/c/1344221Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611517}

ui/webui/resources/cr_components/chromeos/quick_unlock/setup_pin_keyboard.js

@@ -237,12 +237,11 @@ Polymer({
    * Processes the message received from the quick unlock api and hides/shows
    * the problem based on the message.
    * @private
-   * @param {string} newPin
    * @param {chrome.quickUnlockPrivate.CredentialCheck} message The message
    *     received from checkCredential.
    */
-  processPinProblems_: function(newPin, message) {
-    if (newPin && !message.errors.length && !message.warnings.length) {
+  processPinProblems_: function(message) {
+    if (!message.errors.length && !message.warnings.length) {
       this.hideProblem_();
       this.enableSubmit = true;
       this.pinHasPassedMinimumLength_ = true;
@@ -281,9 +280,6 @@ Polymer({
           break;
       }
     }
-
-    if (!newPin)
-      this.enableSubmit = false;
   },
 
   /**
@@ -292,13 +288,13 @@ Polymer({
   onPinChange_: function(e) {
     const newPin = /** @type {{pin: string}} */ (e.detail).pin;
     if (!this.isConfirmStep) {
-      if (this.quickUnlockPrivate) {
+      if (newPin) {
         this.quickUnlockPrivate.checkCredential(
             chrome.quickUnlockPrivate.QuickUnlockMode.PIN, newPin,
-            this.processPinProblems_.bind(this, newPin));
-      }
-      if (!newPin)
+            this.processPinProblems_.bind(this));
+      } else {
         this.enableSubmit = false;
+      }
       return;
     }