Pin keyboard matches red lines (go/cros-quick-unlock-ux).

chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js

Index: chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js
diff --git a/chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js b/chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js
index dfc111d4c5fcd7c32df8aa1e7a95762d0894bfbb..8827527fbb507e6b5ff9f4ea6313039e36937b5a 100644
--- a/chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js
+++ b/chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js
@@ -51,6 +51,12 @@ Polymer({
     this.fire('submit', { pin: this.value });
   },
 
+  /** Changes the color of the submit button if PIN is ready. */
+  changeSubmitColor_: function(pinLength) {
+    var button = this.querySelectorAll('.submit-button .icon-container')[0];
+    button.classList.toggle('ready-background', pinLength > 0);
+  },
+
   /**
    * Fires an update event with the current PIN value. The event will only be
    * fired if the PIN value has actually changed.
@@ -58,8 +64,10 @@ Polymer({
    * @param {string} previous
    */
   onPinValueChange_: function(value, previous) {
-    if (value != previous)
+    if (value != previous) {
       this.fire('pin-change', { pin: value });
+      this.changeSubmitColor_(value.length);

[jdufault, 2016/06/27 19:17:52]

The color should only be blue if value.length > 0, right? If the user erases the
entire PIN it should go back to normal color.

+    }
   },
 
   /** Called when the user wants to erase the last character of the entered