Revert of Decrease the lag when switching between different categories in the Cros wallpaper selector.

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

Index: chrome/browser/resources/chromeos/wallpaper_manager/js/wallpaper_manager.js
diff --git a/chrome/browser/resources/chromeos/wallpaper_manager/js/wallpaper_manager.js b/chrome/browser/resources/chromeos/wallpaper_manager/js/wallpaper_manager.js
index b2318771cf62232685a90940fe9183581c1be174..5d638ecbc448f4446ec4fd6cd1d751026ef33548 100644
--- a/chrome/browser/resources/chromeos/wallpaper_manager/js/wallpaper_manager.js
+++ b/chrome/browser/resources/chromeos/wallpaper_manager/js/wallpaper_manager.js
@@ -17,6 +17,7 @@
   this.dialogDom_ = dialogDom;
   this.document_ = dialogDom.ownerDocument;
   this.enableOnlineWallpaper_ = loadTimeData.valueExists('manifestBaseURL');
+  this.selectedCategory = null;
   this.selectedItem_ = null;
   this.progressManager_ = new ProgressManager();
   this.customWallpaperData_ = null;
@@ -454,6 +455,7 @@
   WallpaperManager.prototype.initThumbnailsGrid_ = function() {
     this.wallpaperGrid_ = $('wallpaper-grid');
     wallpapers.WallpaperThumbnailsGrid.decorate(this.wallpaperGrid_);
+    this.wallpaperGrid_.autoExpands = true;
 
     this.wallpaperGrid_.addEventListener('change', this.onChange_.bind(this));
     this.wallpaperGrid_.addEventListener('dblclick', this.onClose_.bind(this));
@@ -1001,13 +1003,10 @@
       };
 
       var self = this;
-      var numOnlineWallpaper = this.manifest_ ?
-          this.manifest_.wallpaper_list.length : 0;
       var processResults = function(entries) {
         for (var i = 0; i < entries.length; i++) {
           var entry = entries[i];
           var wallpaperInfo = {
-                wallpaperId: numOnlineWallpaper + i,
                 baseURL: entry.name,
                 // The layout will be replaced by the actual value saved in
                 // local storage when requested later. Layout is not important
@@ -1022,7 +1021,6 @@
         }
         if (loadTimeData.getBoolean('isOEMDefaultWallpaper')) {
           var oemDefaultWallpaperElement = {
-              wallpaperId: numOnlineWallpaper + entries.length,
               baseURL: 'OemDefaultWallpaper',
               layout: 'CENTER_CROPPED',
               source: Constants.WallpaperSourceEnum.OEM,
@@ -1069,21 +1067,18 @@
                                        success, errorHandler);
     } else {
       this.document_.body.removeAttribute('custom');
-      var numOnlineWallpaper = this.manifest_ ?
-          this.manifest_.wallpaper_list.length : 0;
-      for (var i = 0; i < numOnlineWallpaper; i++) {
+      for (var key in this.manifest_.wallpaper_list) {
         if (selectedIndex == AllCategoryIndex ||
-            this.manifest_.wallpaper_list[i].categories.indexOf(
+            this.manifest_.wallpaper_list[key].categories.indexOf(
                 selectedIndex - OnlineCategoriesOffset) != -1) {
           var wallpaperInfo = {
-            wallpaperId: i,
-            baseURL: this.manifest_.wallpaper_list[i].base_url,
-            layout: this.manifest_.wallpaper_list[i].default_layout,
+            baseURL: this.manifest_.wallpaper_list[key].base_url,
+            layout: this.manifest_.wallpaper_list[key].default_layout,
             source: Constants.WallpaperSourceEnum.Online,
             availableOffline: false,
-            author: this.manifest_.wallpaper_list[i].author,
-            authorWebsite: this.manifest_.wallpaper_list[i].author_website,
-            dynamicURL: this.manifest_.wallpaper_list[i].dynamic_url
+            author: this.manifest_.wallpaper_list[key].author,
+            authorWebsite: this.manifest_.wallpaper_list[key].author_website,
+            dynamicURL: this.manifest_.wallpaper_list[key].dynamic_url
           };
           var startIndex = wallpaperInfo.baseURL.lastIndexOf('/') + 1;
           var fileName = wallpaperInfo.baseURL.substring(startIndex) +
@@ -1093,7 +1088,7 @@
             wallpaperInfo.availableOffline = true;
           }
           wallpapersDataModel.push(wallpaperInfo);
-          var url = this.manifest_.wallpaper_list[i].base_url +
+          var url = this.manifest_.wallpaper_list[key].base_url +
               Constants.HighResolutionSuffix;
           if (url == this.currentWallpaper_) {
             selectedItem = wallpaperInfo;