DOMUI Prefs: Add a deletable item list type, and use it for startup pages.

chrome/browser/resources/options/deletable_item_list.js

Index: chrome/browser/resources/options/deletable_item_list.js
diff --git a/chrome/browser/resources/options/deletable_item_list.js b/chrome/browser/resources/options/deletable_item_list.js
new file mode 100644
index 0000000000000000000000000000000000000000..e4ea7747df37ee11b9bd92c407a74b20f9985fa2
--- /dev/null
+++ b/chrome/browser/resources/options/deletable_item_list.js
@@ -0,0 +1,119 @@
+// Copyright (c) 2010 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.
+
+cr.define('options', function() {
+  const List = cr.ui.List;
+  const ListItem = cr.ui.ListItem;
+
+  /**
+   * Wraps a list item to make it deletable, adding a button that will trigger a
+   * call to deleteItemAtIndex(index) in the list.
+   * @param {!ListItem} baseItem The list element to wrap.
+   */
+  function DeletableListItem(baseItem) {
+    var el = cr.doc.createElement('div');
+    el.baseItem_ = baseItem;
+    DeletableListItem.decorate(el);
+    return el;
+  }
+
+  /**
+   * Decorates an element as a deletable list item.
+   * @param {!HTMLElement} el The element to decorate.
+   */
+  DeletableListItem.decorate = function(el) {
+    el.__proto__ = DeletableListItem.prototype;
+    el.decorate();
+  };
+
+  DeletableListItem.prototype = {
+    __proto__: ListItem.prototype,
+
+    /**
+     * The list item being wrapped to make in deletable.
+     * @type {!ListItem}
+     * @private
+     */
+    baseItem_: null,
+
+    /** @inheritDoc */
+    decorate: function() {
+      ListItem.prototype.decorate.call(this);
+
+      this.className = 'deletable-item';
+      var contentEl = this.ownerDocument.createElement('div');
+      contentEl.appendChild(this.baseItem_);
+      var closeButtonEl = this.ownerDocument.createElement('button');
+      closeButtonEl.className = 'close-button';
+
+      this.appendChild(contentEl);
+      this.appendChild(closeButtonEl);
+    },
+
+    /**
+     * Returns the list item being wrapped to make in deletable.
+     * @return {!ListItem} The list item being wrapped
+     */
+    get contentItem() {
+      return this.baseItem_;
+    }
+  };
+
+  var DeletableItemList = cr.ui.define('list');
+
+  DeletableItemList.prototype = {
+    __proto__: List.prototype,
+
+    /** @inheritDoc */
+    decorate: function() {
+      List.prototype.decorate.call(this);
+      this.addEventListener('click', this.handleClick_);
+    },
+
+    /** @inheritDoc */
+    createItem: function(value) {
+      var baseItem = this.createItemContents(value);
+      return new DeletableListItem(baseItem);
+    },
+
+    /**
+     * Creates a new list item to use as the main row contents for |value|.
+     * Subclasses should override this instead of createItem.
+     * @param {*} value The value to use for the item.
+     * @return {!ListItem} The newly created list item.
+     */
+    createItemContents: function(value) {
+      List.prototype.createItem.call(this, value);
+    },
+
+    /**
+     * Callback for onclick events.
+     * @param {Event} e The click event object.
+     * @private
+     */
+    handleClick_: function(e) {
+      if (this.disabled)
+        return;
+
+      var target = e.target;
+      if (target.className == 'close-button') {
+        var listItem = this.getListItemAncestor(target);
+        if (listItem)
+          this.deleteItemAtIndex(this.getIndexOfListItem(listItem));
+      }
+    },
+
+    /**
+     * Called when an item should be deleted; subclasses are responsible for
+     * implementing.
+     * @param {number} index The indexd of the item that is being deleted.
+     */
+    deleteItemAtIndex: function(index) {
+    },
+  };
+
+  return {
+    DeletableItemList: DeletableItemList
+  };
+});