Make the third party wallpaper syncable through different devices.

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 302 matching lines @@
       // wallpaper changes.
       WallpaperUtil.requestSyncFS(function() {});
       if (changes[Constants.AccessSyncSurpriseMeEnabledKey]) {
         if (changes[Constants.AccessSyncSurpriseMeEnabledKey].newValue) {
           SurpriseWallpaper.getInstance().next();
         } else {
           SurpriseWallpaper.getInstance().disable();
         }
       }
 
+      if (changes[Constants.AccessLocalWallpaperInfoKey]) {
+        // If the old wallpaper is a third party wallpaper we should remove it
+        // from the local & sync file system to free space.
+        var oldInfo = changes[Constants.AccessLocalWallpaperInfoKey].oldValue;
+        if (oldInfo.url.indexOf(Constants.ThirdPartyWallpaperPrefix) != -1) {
+          WallpaperUtil.deleteWallpaperFromLocalFS(oldInfo.url);
+          WallpaperUtil.deleteWallpaperFromSyncFS(oldInfo.url);
+        }
+      }
+
       if (changes[Constants.AccessSyncWallpaperInfoKey]) {
         var syncInfo = changes[Constants.AccessSyncWallpaperInfoKey].newValue;
 
         Constants.WallpaperSyncStorage.get(
             Constants.AccessSyncSurpriseMeEnabledKey, function(enabledItems) {
           var syncSurpriseMeEnabled =
               enabledItems[Constants.AccessSyncSurpriseMeEnabledKey];
 
           Constants.WallpaperSyncStorage.get(
               Constants.AccessLastSurpriseWallpaperChangedDate,
@@ skipping 28 matching lines @@
                     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();
                   }
+
+                  // If the old wallpaper is a third party wallpaper we should
+                  // remove it from the local & sync file system to free space.
+                  if (localInfo && localInfo.url.indexOf(
+                      Constants.ThirdPartyWallpaperPrefix) != -1) {
+                    WallpaperUtil.deleteWallpaperFromLocalFS(localInfo.url);
+                    WallpaperUtil.deleteWallpaperFromSyncFS(localInfo.url);
+                  }
+
                   WallpaperUtil.saveToLocalStorage(
                       Constants.AccessLocalWallpaperInfoKey, syncInfo);
                 }
               });
             }
           });
         });
       }
     } else {
       // If sync theme is disabled, use values from chrome.storage.local to
       // track wallpaper changes.
       if (changes[Constants.AccessLocalSurpriseMeEnabledKey]) {
         if (changes[Constants.AccessLocalSurpriseMeEnabledKey].newValue) {
           SurpriseWallpaper.getInstance().next();
         } else {
           SurpriseWallpaper.getInstance().disable();
         }
       }
     }
   });
 });
 
 chrome.alarms.onAlarm.addListener(function() {
   SurpriseWallpaper.getInstance().next();
 });
 
-chrome.wallpaperPrivate.onWallpaperChangedBy3rdParty.addListener(function() {
+chrome.wallpaperPrivate.onWallpaperChangedBy3rdParty.addListener(function(
+    wallpaper, thumbnail, layout) {
   WallpaperUtil.saveToLocalStorage(
       Constants.AccessLocalSurpriseMeEnabledKey, false, function() {
     WallpaperUtil.saveToSyncStorage(Constants.AccessSyncSurpriseMeEnabledKey,
                                     false);
   });
   SurpriseWallpaper.getInstance().disable();
+
+  // Make third party wallpaper syncable through different devices.
+  // TODO(xdai): also sync the third party app name.
+  var filename = Constants.ThirdPartyWallpaperPrefix + new Date().getTime();
+  var thumbnailFilename = filename + Constants.CustomWallpaperThumbnailSuffix;
+  WallpaperUtil.storeWallpaperToSyncFS(filename, wallpaper);
+  WallpaperUtil.storeWallpaperToSyncFS(thumbnailFilename, thumbnail);
+  WallpaperUtil.saveWallpaperInfo(filename, layout,
+                                  Constants.WallpaperSourceEnum.Custom);
 });