Fix the issue that wallpaper changes twice when both "onChanged" and "onAlarm" are fired.

chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.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.
 
 var WALLPAPER_PICKER_WIDTH = 574;
 var WALLPAPER_PICKER_HEIGHT = 420;
 
 var wallpaperPickerWindow;
 
 var surpriseWallpaper = null;
@@ skipping 13 matching lines @@
 };
 
 /**
  * Tries to change wallpaper to a new one in the background. May fail due to a
  * network issue.
  */
 SurpriseWallpaper.prototype.tryChangeWallpaper = function() {
   var self = this;
   var onFailure = function() {
     self.retryLater_();
+  };
+  var onNotFound = function() {

[bshe, 2015/03/09 14:16:09]

If not found, I think we should just use a random ONLINE wallpaper instead of
using local copy of RSS. NOT_FOUND is a good indication of no RSS wallpaper.

[xdai1, 2015/03/09 21:07:10]

If not found (404), we randomly set a wallpaper displayed in wallpaper picker.
If other type error occurs, we try to use local rss first, and if we still got
error, set an alarm to retry 1 hour later.

     self.fallbackToLocalRss_();
   };
   // Try to fetch newest rss as document from server first. If any error occurs,
   // proceed with local copy of rss.
   WallpaperUtil.fetchURL(Constants.WallpaperRssURL, 'document', function(xhr) {
     WallpaperUtil.saveToStorage(Constants.AccessRssKey,
         new XMLSerializer().serializeToString(xhr.responseXML), false);
     self.updateSurpriseWallpaper(xhr.responseXML);
-  }, onFailure);
+  }, onFailure, onNotFound);
 };
 
 /**
  * Retries changing the wallpaper 1 hour later. This is called when fetching the
  * rss or wallpaper from server fails.
  * @private
  */
 SurpriseWallpaper.prototype.retryLater_ = function() {
   chrome.alarms.create('RetryAlarm', {delayInMinutes: 60});
 };
@@ skipping 29 matching lines @@
       item = items[i];
       var disableDate = new Date(item.getElementsByTagNameNS(
           Constants.WallpaperNameSpaceURI, 'disableDate')[0].textContent).
               getTime();
       var enableDate = new Date(item.getElementsByTagNameNS(
           Constants.WallpaperNameSpaceURI, 'enableDate')[0].textContent).
               getTime();
       var regionsString = item.getElementsByTagNameNS(
           Constants.WallpaperNameSpaceURI, 'regions')[0].textContent;
       var regions = regionsString.split(', ');
+
+      var self = this;
+      var onSuccess = function(url, layout) {
+        var dateString = new Date().toDateString();
+        WallpaperUtil.saveWallpaperInfo(url, layout,
+            Constants.WallpaperSourceEnum.Online);
+        WallpaperUtil.saveToStorage(
+            Constants.AccessLastSurpriseWallpaperChangedDate,
+            dateString, true);
+      };
+      var onFailure = function() {
+        self.retryLater_();
+      };
+      var onNotFound = function() {
+        self.updateRandomWallpaper_();

[bshe, 2015/03/09 14:16:09]

would be nice to handle the not found case in failure.

[xdai1, 2015/03/09 21:07:10]

Done.

+      };
+
       if (enableDate <= date && disableDate > date &&
           regions.indexOf(navigator.language) != -1) {
-        var self = this;
-        this.setWallpaperFromRssItem_(item,
-                                      function() {},
-                                      function() {
-                                        self.retryLater_();
-                                        self.updateRandomWallpaper_();
-                                      });
+        this.setWallpaperFromRssItem_(item, onSuccess, onFailure, onNotFound);
         return;
       }
     }
   }
   // No surprise wallpaper for today at current locale or fetching rss feed
   // fails. Fallback to use a random one from wallpaper server.
   this.updateRandomWallpaper_();
 };
 
 /**
@@ skipping 28 matching lines @@
       var filtered = manifest.wallpaper_list.filter(function(element) {
         // Older version manifest do not have available_for_surprise_me field.
         // In this case, no wallpaper should be filtered out.
         return element.available_for_surprise_me ||
             element.available_for_surprise_me == undefined;
       });
       var index = Math.floor(Math.random() * filtered.length);
       var wallpaper = filtered[index];
       var wallpaperURL = wallpaper.base_url + Constants.HighResolutionSuffix;
       var onSuccess = function() {
+        WallpaperUtil.saveWallpaperInfo(wallpaperURL, wallpaper.default_layout,
+            Constants.WallpaperSourceEnum.Online);
         WallpaperUtil.saveToStorage(
             Constants.AccessLastSurpriseWallpaperChangedDate,
             dateString,
             true);
       };
       WallpaperUtil.setOnlineWallpaper(wallpaperURL, wallpaper.default_layout,
           onSuccess, self.retryLater_.bind(self));
     }
   });
 };
 
 /**
  * Sets wallpaper to the wallpaper specified by item from rss. If downloading
  * the wallpaper fails, retry one hour later.
  * @param {Element} item The wallpaper rss item element.
  * @param {function} onSuccess Success callback.
  * @param {function} onFailure Failure callback.
+ * @param {function} onNotFound Not found callback.
  * @private
  */
 SurpriseWallpaper.prototype.setWallpaperFromRssItem_ = function(item,
                                                                 onSuccess,
-                                                                onFailure) {
+                                                                onFailure,
+                                                                onNotFound) {
   var url = item.querySelector('link').textContent;
   var layout = item.getElementsByTagNameNS(
         Constants.WallpaperNameSpaceURI, 'layout')[0].textContent;
   var self = this;
   WallpaperUtil.fetchURL(url, 'arraybuffer', function(xhr) {
     if (xhr.response != null) {
       chrome.wallpaperPrivate.setCustomWallpaper(xhr.response, layout, false,
-                                                 'surprise_wallpaper',
-                                                 onSuccess);
+          'surprise_wallpaper', onSuccess(url, layout));
     } else {
       onFailure();
     }
-  }, onFailure);
+  }, onFailure, onNotFound);
 };
 
 /**
  * Disables the wallpaper surprise me feature. Clear all alarms and states.
  */
 SurpriseWallpaper.prototype.disable = function() {
   chrome.alarms.clearAll();
   // Makes last changed date invalid.
   WallpaperUtil.saveToStorage(Constants.AccessLastSurpriseWallpaperChangedDate,
                               '', true);
@@ skipping 76 matching lines @@
     WallpaperUtil.requestSyncFS(function() {});
     if (changes[Constants.AccessSurpriseMeEnabledKey]) {
       if (changes[Constants.AccessSurpriseMeEnabledKey].newValue) {
         SurpriseWallpaper.getInstance().next();
       } else {
         SurpriseWallpaper.getInstance().disable();
       }
     }
 
     if (changes[Constants.AccessSyncWallpaperInfoKey]) {
-      var newValue = changes[Constants.AccessSyncWallpaperInfoKey].newValue;
-      Constants.WallpaperLocalStorage.get(Constants.AccessLocalWallpaperInfoKey,
-                                          function(items) {
-        // Normally, the wallpaper info saved in local storage and sync storage
-        // are the same. If the synced value changed by sync service, they may
-        // different. In that case, change wallpaper to the one saved in sync
-        // storage and update the local value.
-        var localValue = items[Constants.AccessLocalWallpaperInfoKey];
-        if (localValue == undefined ||
-            localValue.url != newValue.url ||
-            localValue.layout != newValue.layout ||
-            localValue.source != newValue.source) {
-          if (newValue.source == Constants.WallpaperSourceEnum.Online) {
-            // TODO(bshe): Consider schedule an alarm to set online wallpaper
-            // later when failed. Note that we need to cancel the retry if user
-            // set another wallpaper before retry alarm invoked.
-            WallpaperUtil.setOnlineWallpaper(newValue.url, newValue.layout,
-              function() {}, function() {});
-          } else if (newValue.source == Constants.WallpaperSourceEnum.Custom) {
-            WallpaperUtil.setCustomWallpaperFromSyncFS(newValue.url,
-                                                       newValue.layout);
-          } else if (newValue.source == Constants.WallpaperSourceEnum.Default) {
-            chrome.wallpaperPrivate.resetWallpaper();
+      var syncInfo = changes[Constants.AccessSyncWallpaperInfoKey].newValue;
+
+      Constants.WallpaperSyncStorage.get(Constants.AccessSurpriseMeEnabledKey,
+                                         function(enabledItems) {
+        var syncSurpriseMeEnabled =
+            enabledItems[Constants.AccessSurpriseMeEnabledKey];
+
+        Constants.WallpaperSyncStorage.get(
+            Constants.AccessLastSurpriseWallpaperChangedDate, function(items) {
+          var syncLastSurpriseMeChangedDate =
+              items[Constants.AccessLastSurpriseWallpaperChangedDate];
+
+          var today = new Date().toDateString();
+          // If SurpriseMe is enabled and surprise wallpaper hasn't been changed
+          // today, we should not sync the change, instead onAlarm() will be
+          // triggered to update a surprise me wallpaper.
+          if (!syncSurpriseMeEnabled ||
+              (syncSurpriseMeEnabled &&
+                  syncLastSurpriseMeChangedDate == today)) {
+            Constants.WallpaperLocalStorage.get(
+                Constants.AccessLocalWallpaperInfoKey, function(infoItems) {
+              var localInfo = infoItems[Constants.AccessLocalWallpaperInfoKey];
+              // Normally, the wallpaper info saved in local storage and sync
+              // storage are the same. If the synced value changed by sync
+              // service, they may different. In that case, change wallpaper to
+              // the one saved in sync storage and update the local value.
+              if (localInfo == undefined ||
+                  localInfo.url != syncInfo.url ||
+                  localInfo.layout != syncInfo.layout ||
+                  localInfo.source != syncInfo.source) {
+                if (syncInfo.source == Constants.WallpaperSourceEnum.Online) {
+                  // TODO(bshe): Consider schedule an alarm to set online
+                  // wallpaper later when failed. Note that we need to cancel
+                  // the retry if user set another wallpaper before retry alarm
+                  // invoked.
+                  WallpaperUtil.setOnlineWallpaper(syncInfo.url,
+                      syncInfo.layout, function() {}, function() {});
+                } else if (syncInfo.source ==
+                              Constants.WallpaperSourceEnum.Custom) {
+                  WallpaperUtil.setCustomWallpaperFromSyncFS(syncInfo.url,
+                                                             syncInfo.layout);
+                } else if (syncInfo.source ==
+                              Constants.WallpaperSourceEnum.Default) {
+                  chrome.wallpaperPrivate.resetWallpaper();
+                }
+                WallpaperUtil.saveToStorage(
+                    Constants.AccessLocalWallpaperInfoKey, syncInfo, false);
+              }
+            });
           }
-          WallpaperUtil.saveToStorage(Constants.AccessLocalWallpaperInfoKey,
-                                      newValue, false);
-        }
+        });
       });
     }
   });
 });
 
 chrome.alarms.onAlarm.addListener(function() {
   SurpriseWallpaper.getInstance().next();
 });