Fix toast not showing when the image to download was already downloaded

Clover/app/src/main/java/org/floens/chan/core/saver/ImageSaveTask.java

@@ -214,8 +214,13 @@ public class ImageSaveTask implements Runnable, FileCache.DownloadedCallback {
     }
 
     private void postFinished(final boolean success) {
+        AndroidUtils.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
                 callback.imageSaveTaskFinished(ImageSaveTask.this, success);
             }
+        });
+    }
 
     public interface ImageSaveTaskCallback {
         void imageSaveTaskFinished(ImageSaveTask task, boolean success);