Fix custom wallpaper going back from wallpaper 2 to wallpaper 1

chrome/browser/resources/chromeos/wallpaper_manager/js/wallpaper_images_grid.js

 // Copyright (c) 2013 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('wallpapers', function() {
   /** @const */ var ArrayDataModel = cr.ui.ArrayDataModel;
   /** @const */ var Grid = cr.ui.Grid;
   /** @const */ var GridItem = cr.ui.GridItem;
   /** @const */ var GridSelectionController = cr.ui.GridSelectionController;
   /** @const */ var ListSingleSelectionModel = cr.ui.ListSingleSelectionModel;
@@ skipping 229 matching lines @@
     },
     set selectedItem(selectedItem) {
       var index = this.dataModel.indexOf(selectedItem);
       this.inProgramSelection_ = true;
       this.selectionModel.leadIndex = index;
       this.selectionModel.selectedIndex = index;
       this.inProgramSelection_ = false;
     },
 
     /**
+     * Inserts newElement at the position specified by index.
+     * @param {number} index The index of the newElement to insert.
+     * @type {!Object} Wallpaper information inserted into the data model.

[flackr, 2013/04/15 15:02:02]

@param {!Object} newElement
Although I'd prefer this to be called wallpaperInfo instead of newElement since
the list being inserted into contains wallpaper information.

[bshe, 2013/04/15 15:22:10]

Done.

+     */
+    insertElement: function(index, newElement) {
+      // splice may dispatch a change event because the position of selected
+      // element changing. But the actual selected element didn't change after
+      // splice. Sets inProgramSelection to true to disable the event handler of
+      // change event. Otherwise, wallpaper may reset to previous one as

[flackr, 2013/04/15 15:02:02]

Can we not we prevent handling a change event which doesn't change the actual
selected element?

[bshe, 2013/04/15 15:22:10]

Sorry, just to confirm. Do you mean we check if the selected element is the same
as previous one in the event handler? And prevent handling if it is the same as
previous one?

On 2013/04/15 15:02:02, flackr wrote:

[flackr, 2013/04/15 20:00:54]

Yes.

On 2013/04/15 15:22:10, bshe wrote:

[bshe, 2013/04/15 23:38:22]

Done.

+      // described in http://crbug.com/229036.
+      this.inProgramSelection_ = true;
+      this.dataModel.splice(index, 0, newElement);
+      this.inProgramSelection_ = false;
+    },
+
+    /**
      * Forces re-display, size re-calculation and focuses grid.
      */
     updateAndFocus: function() {
       // Recalculate the measured item size.
       this.measured_ = null;
       this.columns = 0;
       this.redraw();
       this.focus();
     },
 
@@ skipping 27 matching lines @@
       // to make sure checkmark shows correctly.
       this.updateActiveThumb_();
     }
   };
 
   return {
     WallpaperSourceEnum: WallpaperSourceEnum,
     WallpaperThumbnailsGrid: WallpaperThumbnailsGrid
   };
 });