Make the third party wallpaper syncable through different devices.

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

Index: chrome/browser/resources/chromeos/wallpaper_manager/js/util.js
diff --git a/chrome/browser/resources/chromeos/wallpaper_manager/js/util.js b/chrome/browser/resources/chromeos/wallpaper_manager/js/util.js
index de8c5187886a5fd7e56ce86e4c502f26c39ce69a..3baf9a7ff605208201ecd06de389584a30dbb6e0 100644
--- a/chrome/browser/resources/chromeos/wallpaper_manager/js/util.js
+++ b/chrome/browser/resources/chromeos/wallpaper_manager/js/util.js
@@ -77,13 +77,19 @@ WallpaperUtil.deleteWallpaperFromSyncFS = function(wallpaperFilename) {
                     function(fe) {
                       fe.remove(function() {}, null);
                     },
-                    WallpaperUtil.onFileSystemError);
+                    function(e) {
+                      if (e.name != 'NotFoundError')

[bshe, 2016/01/13 18:43:17]

would be good to add a command why we want to ignore NotFoundError

[xdai1, 2016/01/14 23:03:51]

Done.

+                        WallpaperUtil.onFileSystemError(e);
+                    });
     fs.root.getFile(thumbnailFilename,
                     {create: false},
                     function(fe) {
                       fe.remove(function() {}, null);
                     },
-                    WallpaperUtil.onFileSystemError);
+                    function(e) {
+                      if (e.name != 'NotFoundError')
+                        WallpaperUtil.onFileSystemError(e);
+                    });
   };
   WallpaperUtil.requestSyncFS(success);
 };
@@ -247,7 +253,7 @@ WallpaperUtil.setCustomWallpaperFromSyncFS = function(
                 WallpaperUtil.storeWallpaperToLocalFS(wallpaperFilename,
                     reader.result, Constants.WallpaperDirNameEnum.ORIGINAL);
                 WallpaperUtil.storeWallpaperToLocalFS(wallpaperFilename,
-                    reader.result, Constants.WallpaperDirNameEnum.THUMBNAIL);
+                    thumbnailData, Constants.WallpaperDirNameEnum.THUMBNAIL);

[bshe, 2016/01/08 19:56:39]

this seem to fix a different issue. do you mind land in a different CL?

[xdai1, 2016/01/08 20:17:48]

Sure! I will separate it in another CL.

                 if (onSuccess)
                   onSuccess();
               });