MD History: Update sign in state in data source

chrome/browser/resources/md_history/app.crisper.js

Index: chrome/browser/resources/md_history/app.crisper.js
diff --git a/chrome/browser/resources/md_history/app.crisper.js b/chrome/browser/resources/md_history/app.crisper.js
index e6c08baa1f5371681f39411a52f209fb17b4ecca..603667cc0e059893dea857d072f0471581c7b844 100644
--- a/chrome/browser/resources/md_history/app.crisper.js
+++ b/chrome/browser/resources/md_history/app.crisper.js
@@ -5331,7 +5331,7 @@ cr.define('md_history', function() {
 
 Polymer({
   is: 'history-app',
-  behaviors: [ Polymer.IronScrollTargetBehavior ],
+  behaviors: [ Polymer.IronScrollTargetBehavior, WebUIListenerBehavior ],
   properties: {
     showSidebarFooter: Boolean,
     hasSyncedResults: Boolean,
@@ -5397,6 +5397,9 @@ Polymer({
     document.addEventListener('canExecute', this.onCanExecute_.bind(this));
     document.addEventListener('command', this.onCommand_.bind(this));
   },
+  attached: function() {
+    this.addWebUIListener('sign-in-state-updated', this.updateSignInState.bind(this));
+  },
   onFirstRender: function() {
     setTimeout(function() {
       chrome.send('metricsHandler:recordTime', [ 'History.ResultsRenderedTime', window.performance.now() ]);