Stop checking for null selectionModel field.

chrome/browser/resources/options/language_list.js

 // Copyright (c) 2012 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 */ var ArrayDataModel = cr.ui.ArrayDataModel;
   /** @const */ var DeletableItem = options.DeletableItem;
   /** @const */ var DeletableItemList = options.DeletableItemList;
   /** @const */ var List = cr.ui.List;
   /** @const */ var ListItem = cr.ui.ListItem;
@@ skipping 370 matching lines @@
           languageCodesInCsv.split(','));
       this.load_(languageCodes);
     },
 
     /**
      * Loads given language list.
      * @param {!Array} languageCodes List of language codes.
      * @private
      */
     load_: function(languageCodes) {
+      if (!this.selectionModel)

[Kevin Bailey, 2016/01/26 15:00:40]

Sorry, it was unclear to me what you preferred. Something like this?

(If this.selectionModel is getting set when this.dataModel is set, then I'm
simply not seeing it.)

[Dan Beam, 2016/01/26 19:38:53]

I would prefer load_ only get called after being decorated, but if you stick
with this:

  if (!this.selectionModel) {
    // Wait until decorate() is called.
    return;
  }

[Kevin Bailey, 2016/01/26 22:21:46]

Done.

+        return;
       // Preserve the original selected index. See comments below.
-      var originalSelectedIndex = (this.selectionModel ?
-                                   this.selectionModel.selectedIndex : -1);
+      var originalSelectedIndex = this.selectionModel.selectedIndex;
       this.dataModel = new ArrayDataModel(languageCodes);

[Dan Beam, 2016/01/26 19:38:53]

doing

  this.dataModel = ...;

triggers an ES5 setter in an ancestor class that calls:

  this.selectionModel.clear();

how does that succeed?  does it also need to be updated?

       if (originalSelectedIndex >= 0 &&
           originalSelectedIndex < this.dataModel.length) {
         // Restore the original selected index if the selected index is
-        // valid after the data model is loaded. This is neeeded to keep
+        // valid after the data model is loaded. This is needed to keep
         // the selected language after the languge is added or removed.
         this.selectionModel.selectedIndex = originalSelectedIndex;
         // The lead index should be updated too.
         this.selectionModel.leadIndex = originalSelectedIndex;
-      } else if (this.dataModel.length > 0) {
-        // Otherwise, select the first item if it's not empty.
-        // Note that ListSingleSelectionModel won't select an item
-        // automatically, hence we manually select the first item here.
-        this.selectionModel.selectedIndex = 0;

[Dan Beam, 2016/01/26 19:38:53]

revert this now

       }
     },
 
     /**
      * Saves the preference.
      */
     savePreference_: function() {
       chrome.send('updateLanguageList', [this.dataModel.slice()]);
       cr.dispatchSimpleEvent(this, 'save');
     },
@@ skipping 18 matching lines @@
       }
       return filteredLanguageCodes;
     },
   };
 
   return {
     LanguageList: LanguageList,
     LanguageListItem: LanguageListItem
   };
 });