MD History: Add icon in top right of page when showing synced results

chrome/browser/resources/md_history/history_toolbar.js

 // Copyright 2015 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: 'history-toolbar',
   properties: {
     // Number of history items currently selected.
     // TODO(calamity): bind this to
     // listContainer.selectedItem.selectedPaths.length.
@@ skipping 24 matching lines @@
       type: Boolean,
       value: false
     },
 
     hasDrawer: {
       type: Boolean,
       observer: 'hasDrawerChanged_',
       reflectToAttribute: true,
     },
 
+    showSyncNotice: Boolean,
+
     // Whether domain-grouped history is enabled.
     isGroupedMode: {
       type: Boolean,
       reflectToAttribute: true,
     },
 
     // The period to search over. Matches BrowsingHistoryHandler::Range.
     groupedRange: {
       type: Number,
       value: 0,
@@ skipping 34 matching lines @@
   },
 
   /**
    * @param {!CustomEvent} event
    * @private
    */
   onSearchChanged_: function(event) {
     this.searchTerm = /** @type {string} */ (event.detail);
   },
 
+  /** @private */
+  onInfoButtonTap_: function() {
+    this.$.syncNotice.get().then(function(dropdown) {
+      dropdown.positionTarget = this.$$('#info-button-icon');
+      // It is possible for this listener to trigger while the dialog is
+      // closing. Ensure the dialog is fully closed before reopening it.
+      if (dropdown.style.display == 'none')
+        dropdown.open();
+    }.bind(this));
+  },
+
   onClearSelectionTap_: function() {
     this.fire('unselect-all');
   },
 
   onDeleteTap_: function() {
     this.fire('delete-selected');
   },
 
   get searchBar() {
     return this.$['main-toolbar'].getSearchField();
@@ skipping 21 matching lines @@
     // TODO(calamity): Fix the format of these dates.
     return loadTimeData.getStringF(
       'historyInterval', queryStartTime, queryEndTime);
   },
 
   /** @private */
   hasDrawerChanged_: function() {
     this.updateStyles();
   },
 });