Asynchronously load a content filter given its @identifier. The filter must have been
previously stored using webkit_user_content_filter_store_save().
When the operation is finished, @callback will be invoked, which then can use
webkit_user_content_filter_store_load_finish() to obtain the resulting filter.
Asynchronously load a content filter given its @identifier. The filter must have been previously stored using webkit_user_content_filter_store_save().
When the operation is finished, @callback will be invoked, which then can use webkit_user_content_filter_store_load_finish() to obtain the resulting filter.