MD History: Display synced tabs history

chrome/browser/resources/md_history/side_bar.js

+// Copyright 2016 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.
+
+Polymer({
+  is: 'side-bar',
+
+  properties: {
+    selectedDisplay: {
+      type: String,
+      value: 'history-button'
+    }
+  },
+
+  changeDisplay: function(e) {
+    this.selectedPage = e.currentTarget.id;
+
+    var currentButton =
+        Polymer.dom(this.root).querySelector('.selected');
+    currentButton.classList.remove('selected');
+
+    var buttonPressed =
+        Polymer.dom(this.root).querySelector('#' + e.currentTarget.id);

[calamity, 2016/02/11 00:23:31]

Can't you just use e.currentTarget?

[yingran, 2016/02/11 02:06:36]

nup

polymer-mini-extracted.js:1233 Uncaught SyntaxError: Failed to execute
'querySelector' on 'DocumentFragment': '[object HTMLDivElement]' is not a valid
selector.

+    buttonPressed.classList.add('selected');
+
+    this.fire('switch-display', { display: this.selectedPage });
+  }
+});