MD History: Show 'no synced tabs' when tab sync is disabled

chrome/browser/resources/md_history/app.js

Index: chrome/browser/resources/md_history/app.js
diff --git a/chrome/browser/resources/md_history/app.js b/chrome/browser/resources/md_history/app.js
index 05de2358758b1043b532324fa538c39f21026ca9..c9a41b995f83e9280ce30cd22621e6bd7d05473c 100644
--- a/chrome/browser/resources/md_history/app.js
+++ b/chrome/browser/resources/md_history/app.js
@@ -200,8 +200,14 @@ Polymer({
    * @param {boolean} isTabSyncEnabled Is tab sync enabled for this profile?
    */
   setForeignSessions: function(sessionList, isTabSyncEnabled) {
-    if (!isTabSyncEnabled)
+    if (!isTabSyncEnabled) {
+      var syncedDeviceManagerElem =
+      /** @type {HistorySyncedDeviceManagerElement} */this
+          .$$('history-synced-device-manager');
+      if (syncedDeviceManagerElem)
+        syncedDeviceManagerElem.tabSyncDisabled();
       return;
+    }
 
     this.set('queryResult_.sessionList', sessionList);
   },