When pin-keyboard comes up the input element is of focus.

ui/login/account_picker/user_pod_row.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 User pod row implementation.
  */
 
 cr.define('login', function() {
   /**
@@ skipping 1119 matching lines @@
 
     setPinVisibility: function(visible) {
       var elements = [this, this.authElement, this.imageElement,
                       this.signInElement, this.pinContainer];
 
       for (var idx = 0; idx < elements.length; idx++) {
         var currentElement = elements[idx];
         currentElement.classList.toggle('pin-enabled', visible);
         currentElement.classList.toggle('pin-disabled', !visible);
       }
+
+      // Set the focus to the input element after showing/hiding pin keyboard.
+      if (visible)
+        this.pinKeyboard.focus();
+      else
+        this.mainInput.focus();
     },
 
     setUserPodIconType: function(userTypeClass) {
       this.userTypeIconAreaElement.classList.add(userTypeClass);
       this.userTypeIconAreaElement.hidden = false;
     },
 
     /**
      * The user that this pod represents.
      * @type {!Object}
@@ skipping 2347 matching lines @@
        if (pod && pod.multiProfilesPolicyApplied) {
          pod.userTypeBubbleElement.classList.remove('bubble-shown');
        }
      }
   };
 
   return {
     PodRow: PodRow
   };
 });