Fixed header bar UI behaviour.

chrome/browser/resources/chromeos/login/header_bar.js

Index: chrome/browser/resources/chromeos/login/header_bar.js
diff --git a/chrome/browser/resources/chromeos/login/header_bar.js b/chrome/browser/resources/chromeos/login/header_bar.js
index 2833dfa8bedd3444dfa1b8160fafc64c19847820..fe8bdae47d06539ebd4bb34d7934659f46aba28b 100644
--- a/chrome/browser/resources/chromeos/login/header_bar.js
+++ b/chrome/browser/resources/chromeos/login/header_bar.js
@@ -7,13 +7,6 @@
  */
 
 cr.define('login', function() {
-  // Network state constants.
-  /** @const */ var NET_STATE = {
-    OFFLINE: 0,
-    ONLINE: 1,
-    PORTAL: 2
-  };
-
   /**
    * Creates a header bar element.
    * @constructor
@@ -27,6 +20,9 @@ cr.define('login', function() {
     // Whether guest button should be shown when header bar is in normal mode.
     showGuest_: false,
 
+    // Current UI state of the sign-in screen.
+    signinUIState_: SIGNIN_UI_STATE.HIDDEN,
+
     /** @override */
     decorate: function() {
       $('shutdown-header-bar-item').addEventListener('click',
@@ -136,12 +132,12 @@ cr.define('login', function() {
     },
 
     /**
-     * If true then sign in UI is active and header controls
-     * should change accordingly.
-     * @type {boolean}
+     * Update current header bar UI.
+     * @type {number} state Current state of the sign-in screen
+     *                      (see SIGNIN_UI_STATE).
      */
-    set signinUIActive(value) {
-      this.signinUIActive_ = value;
+    set signinUIState(state) {
+      this.signinUIState_ = state;
       this.updateUI_();
     },
 
@@ -159,11 +155,14 @@ cr.define('login', function() {
      * @private
      */
     updateUI_: function() {
-      $('add-user-button').hidden = this.signinUIActive_;
-      $('cancel-add-user-button').hidden =
-          !this.signinUIActive_ || !this.allowCancel_;
-      $('guest-user-header-bar-item').hidden =
-          this.signinUIActive_ || !this.showGuest_;
+      var gaiaIsActive = (this.signinUIState_ == SIGNIN_UI_STATE.GAIA_SIGNIN);
+      var accountPickerIsActive =
+          (this.signinUIState_ == SIGNIN_UI_STATE.ACCOUNT_PICKER);
+
+      $('add-user-button').hidden = !accountPickerIsActive;
+      $('cancel-add-user-button').hidden = accountPickerIsActive ||
+          !this.allowCancel_;
+      $('guest-user-header-bar-item').hidden = gaiaIsActive || !this.showGuest_;
       $('add-user-header-bar-item').hidden =
           $('add-user-button').hidden && $('cancel-add-user-button').hidden;
     },