Convert wallpaper picker to v2 app

chrome/browser/resources/chromeos/wallpaper_manager/js/wallpaper_manager.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.
 
 /**
  * WallpaperManager constructor.
  *
  * WallpaperManager objects encapsulate the functionality of the wallpaper
  * manager extension.
  *
  * @constructor
  * @param {HTMLElement} dialogDom The DOM node containing the prototypical
  *     extension UI.
  */
 
 function WallpaperManager(dialogDom) {
   this.dialogDom_ = dialogDom;
   this.document_ = dialogDom.ownerDocument;
   this.selectedCategory = null;
   this.butterBar_ = new ButterBar(this.dialogDom_);
   this.customWallpaperData_ = null;
   this.currentWallpaper_ = null;
+  this.wallpaperRequest_ = null;
   this.fetchManifest_();
-  this.initDom_();
 }
 
 // Anonymous 'namespace'.
 // TODO(bshe): Get rid of anonymous namespace.
 (function() {
 
   /**
    * Base URL of the manifest file.
    */
   /** @const */ var ManifestBaseURL = 'https://commondatastorage.googleapis.' +
@@ skipping 39 matching lines @@
     } catch (e) {
       this.butterBar_.showError_('Failed to parse manifest.');
       this.manifest_ = {};
     }
   };
 
   /**
    * Requests wallpaper manifest file from server.
    */
   WallpaperManager.prototype.fetchManifest_ = function() {
-    var xhr = new XMLHttpRequest();
     var locale = navigator.language;
     var urls = [
         ManifestBaseURL + locale + '.json',
         // Fallback url. Use 'en' locale by default.
         ManifestBaseURL + 'en.json'];
+    var self = this;
 
-    for (var i = 0; i < urls.length; i++) {
-      xhr.open('GET', urls[i], false);
+    var asyncFetchManifestFromUrls = function(urls, func, callback) {

[flackr, 2012/11/13 16:18:30]

To make this a bit easier to read, perhaps you could have a successCallback
taking the response data and failureCallback showing an error. These can be
moved out to functions in the WallpaperManager.prototype.

[bshe, 2012/11/13 19:33:22]

Done.

+      var index = 0;
+      var loop = {
+        next: function() {
+          if (index < urls.length) {
+            func(loop, urls[index]);
+            index++;
+          } else {
+            callback();
+          }
+        },
+
+        done: function() {
+          callback();

[flackr, 2012/11/13 16:18:30]

It looks like if there are no manifests we will no longer show the connection
failed message, is this by design?

[bshe, 2012/11/13 19:33:22]

No. That was a mistake. Fixed it in new patch.

On 2012/11/13 16:18:30, flackr wrote:

+        }
+      };
+      loop.next();
+    }

[flackr, 2012/11/13 16:18:30]

Need semicolon at end of line.

[bshe, 2012/11/13 19:33:22]

Done.

+
+    var fetchManifestAsync = function(loop, url) {
+      var xhr = new XMLHttpRequest();
+      xhr.open('GET', url, true);
       try {
         xhr.send(null);
-        // TODO(bshe): We should save the downloaded manifest to local disk.
-        // Other components may want to use it (i.e. screen saver).
-        if (xhr.status === 200) {
-          this.parseManifest_(xhr.responseText);
-          return;
-        }
+        xhr.addEventListener('load', function(e) {
+          // TODO(bshe): We should save the downloaded manifest to local disk.
+          // Other components may want to use it (e.g. screen saver).
+          if (xhr.status === 200) {
+            self.parseManifest_(xhr.responseText);
+            self.initDom_();
+            loop.done();

[flackr, 2012/11/13 16:18:30]

As the code is currently, you'll call initDom twice, once by calling
loop.done().

[bshe, 2012/11/13 19:33:22]

Should be fixed in the new patch.

On 2012/11/13 16:18:30, flackr wrote:

+          } else {
+            loop.next();
+          }
+        });
       } catch (e) {
-        this.manifest_ = {};
-        this.butterBar_.showError_(str('connectionFailed'));
-        return;
+        self.manifest_ = {};
+        self.butterBar_.showError_(str('connectionFailed'));
+        loop.done();
       }
     }

[flackr, 2012/11/13 16:18:30]

Semicolon at end of line.

[bshe, 2012/11/13 19:33:22]

Done.

-    this.manifest_ = {};
-    this.butterBar_.showError_(str('connectionFailed'));
+
+    asyncFetchManifestFromUrls(urls, fetchManifestAsync, this.initDom_);
 
     // TODO(bshe): Fall back to saved manifest if there is a problem fetching
     // manifest from server.
   };
 
   /**
    * One-time initialization of various DOM nodes.
    */
   WallpaperManager.prototype.initDom_ = function() {
     i18nTemplate.process(this.document_, loadTimeData);
@@ skipping 283 matching lines @@
             selectedItem = wallpaperInfo;
           }
         }
       }
       this.wallpaperGrid_.dataModel = wallpapersDataModel;
       this.wallpaperGrid_.selectedItem = selectedItem;
     }
   };
 
 })();