MD Bookmarks: Show toolbar overlay when multiple items are selected

chrome/browser/resources/md_bookmarks/toolbar.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-toolbar',
 
   behaviors: [
     bookmarks.StoreClient,
   ],
 
   properties: {
     /** @private */
     searchTerm_: {
       type: String,
       observer: 'onSearchTermChanged_',
     },
 
     sidebarWidth: {
       type: String,
       observer: 'onSidebarWidthChanged_',
     },
+
+    showSelectionOverlay: {
+      type: Boolean,
+      computed: 'shouldShowSelectionOverlay_(selectedCount_)',
+      readOnly: true,
+      reflectToAttribute: true,
+    },
+
+    /** @private */
+    selectedCount_: Number,
   },
 
   attached: function() {
     this.watch('searchTerm_', function(state) {
       return state.search.term;
     });
+    this.watch('selectedCount_', function(state) {
+      return state.selection.items.size;
+    });
+    this.updateFromStore();
   },
 
   /** @return {CrToolbarSearchFieldElement} */
   get searchField() {
     return /** @type {CrToolbarElement} */ (this.$$('cr-toolbar'))
         .getSearchField();
   },
 
   /**
    * @param {Event} e
@@ skipping 12 matching lines @@
   },
 
   /** @private */
   onAddBookmarkTap_: function() {
     var dialog =
         /** @type {BookmarksEditDialogElement} */ (this.$.addDialog.get());
     dialog.showAddDialog(false, assert(this.getState().selectedFolder));
     this.closeDropdownMenu_();
   },
 
+  /** @private */
   onAddFolderTap_: function() {
     var dialog =
         /** @type {BookmarksEditDialogElement} */ (this.$.addDialog.get());
     dialog.showAddDialog(true, assert(this.getState().selectedFolder));
     this.closeDropdownMenu_();
   },
 
   /** @private */
   onImportTap_: function() {
     chrome.bookmarks.import();
     this.closeDropdownMenu_();
   },
 
   /** @private */
   onExportTap_: function() {
     chrome.bookmarks.export();
     this.closeDropdownMenu_();
   },
 
   /** @private */
+  onClearSelectionTap_: function() {
+    this.dispatch(bookmarks.actions.deselectItems());
+  },
+
+  /** @private */
   closeDropdownMenu_: function() {
     var menu = /** @type {!CrActionMenuElement} */ (this.$.dropdown);
     menu.close();
   },
 
   /**
    * @param {Event} e
    * @private
    */
   onSearchChanged_: function(e) {
     var searchTerm = /** @type {string} */ (e.detail);
     if (searchTerm != this.searchTerm_)
       this.dispatch(bookmarks.actions.setSearchTerm(searchTerm));
   },
 
+  /** @private */
   onSidebarWidthChanged_: function() {
     this.style.setProperty('--sidebar-width', this.sidebarWidth);
   },
 
   /** @private */
   onSearchTermChanged_: function() {
     this.searchField.setValue(this.searchTerm_ || '');
   },
 
   /**
    * @return {boolean}
    * @private
    */
   hasSearchTerm_: function() {
     return !!this.searchTerm_;
   },
+
+  /**
+   * @return {boolean}
+   * @private
+   */
+  shouldShowSelectionOverlay_: function() {
+    return this.selectedCount_ > 1;
+  },
+
+  /**
+   * @return {string}
+   * @private
+   */
+  numberOfItemsSelected_: function() {
+    return loadTimeData.getStringF('itemsSelected', this.selectedCount_);
+  },
 });