[MD Bookmarks] Add Select for Bookmarks.

chrome/browser/resources/md_bookmarks/item.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: 'bookmarks-item',
 
   properties: {
     /** @type {BookmarkTreeNode} */
     item: {
       type: Object,
       observer: 'onItemChanged_',
     },
 
     isFolder_: Boolean,
+
+    isSelected: {
+      type: Boolean,
+      reflectToAttribute: true,
+    },
   },
 
   observers: [
     'updateFavicon_(item.url)',
   ],
 
+  listeners: {
+    'click': 'onSingleClick_',
+    'dblclick': 'onDoubleClick_',
+  },
+
   /**
    * @param {Event} e
    * @private
    */
   onMenuButtonOpenTap_: function(e) {
+    e.stopPropagation();
     this.fire('open-item-menu', {
       target: e.target,
-      item: this.item
+      item: this.item,
     });
   },
 
   /** @private */
   onItemChanged_: function() {
     this.isFolder_ = !(this.item.url);
   },
 
-  /** @private */
+  /**
+   * @param {Event} e
+   * @private
+   */
+  onSingleClick_: function(e) {
+    if (e.shiftKey)
+      this.fire('shift-select-multiple-items', {
+        item: this.item,
+      });
+    else if (e.ctrlKey)
+      this.fire('ctrl-select-multiple-items', {
+        item: this.item,
+      });
+    else
+      this.fire('select-single-item', {
+        item: this.item,
+      });
+  },
+
+  /**
+   * @param {Event} e
+   * @private
+   */
+  onDoubleClick_: function(e) {
+    /* TODO(jiaxi): Add double click later. */
+  },
+
+  /**
+   * @param {Event} e
+   * @private
+   */
   updateFavicon_: function(url) {
     this.$.icon.style.backgroundImage = cr.icon.getFavicon(url);
   },
 });