[MD Bookmarks] Add bookmark count to context menu for multiple items.

chrome/browser/resources/md_bookmarks/command_manager.js

 // Copyright 2017 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.
 
 /**
  * @fileoverview Element which shows context menus and handles keyboard
  * shortcuts.
  */
 cr.define('bookmarks', function() {
 
@@ skipping 14 matching lines @@
             Command.COPY,
             Command.DELETE,
             // <hr>
             Command.OPEN_NEW_TAB,
             Command.OPEN_NEW_WINDOW,
             Command.OPEN_INCOGNITO,
           ];
         },
       },
 
-      /** @type {Set<string>} */
-      menuIds_: Object,
+      /** @private {Set<string>} */
+      menuIds_: {
+        type: Object,
+        observer: 'onMenuIdsChanged_',
+      },
+
+      /** @private */
+      hasAnySublabel_: {
+        type: Boolean,
+        reflectToAttribute: true,
+      }
     },
 
     attached: function() {
       assert(CommandManager.instance_ == null);
       CommandManager.instance_ = this;
 
       /** @private {function(!Event)} */
       this.boundOnOpenItemMenu_ = this.onOpenItemMenu_.bind(this);
       document.addEventListener('open-item-menu', this.boundOnOpenItemMenu_);
 
@@ skipping 299 matching lines @@
       } else {
         this.openCommandMenuAtPosition(e.detail.x, e.detail.y);
       }
     },
 
     /**
      * @param {Event} e
      * @private
      */
     onCommandClick_: function(e) {
-      this.handle(e.target.getAttribute('command'), assert(this.menuIds_));
+      this.handle(
+          e.currentTarget.getAttribute('command'), assert(this.menuIds_));
       this.closeCommandMenu();
     },
 
     /**
      * @param {!Event} e
      * @private
      */
     onKeydown_: function(e) {
       var selection = this.getState().selection.items;
       if (e.target == document.body)
@@ skipping 49 matching lines @@
         case Command.OPEN_INCOGNITO:
           label = multipleNodes ? 'menuOpenAllIncognito' : 'menuOpenIncognito';
           break;
       }
 
       return loadTimeData.getString(assert(label));
     },
 
     /**
      * @param {Command} command
+     * @return {string}
+     * @private
+     */
+    getCommandSublabel_: function(command) {
+      var multipleNodes = this.menuIds_.size > 1 ||
+          this.containsMatchingNode_(this.menuIds_, function(node) {
+            return !node.url;
+          });
+      switch (command) {
+        case Command.OPEN_NEW_TAB:
+          var urls = this.expandUrls_(this.menuIds_);
+          return multipleNodes && urls.length > 0 ? String(urls.length) : '';
+        default:
+          return '';
+      }
+    },
+
+    /** @private */
+    onMenuIdsChanged_: function() {
+      if (!this.menuIds_)
+        return;
+
+      this.hasAnySublabel_ = this.menuCommands_.some(function(command) {
+        return this.getCommandSublabel_(command) != '';
+      }.bind(this));
+    },
+
+    /**
+     * @param {Command} command
      * @return {boolean}
      * @private
      */
     showDividerAfter_: function(command) {
       return command == Command.DELETE;
     },
   });
 
   /** @private {bookmarks.CommandManager} */
   CommandManager.instance_ = null;
 
   /** @return {!bookmarks.CommandManager} */
   CommandManager.getInstance = function() {
     return assert(CommandManager.instance_);
   };
 
   return {
     CommandManager: CommandManager,
   };
 });