Generalize Previews Type code

components/previews/core/previews_black_list.h

Index: components/previews/core/previews_black_list.h
diff --git a/components/previews/core/previews_black_list.h b/components/previews/core/previews_black_list.h
index 7bd575302df3d7c9531c494e9c5dcd47ddd8cc39..2bfe91e31aec109edc12cb7f126e40fe0109f92e 100644
--- a/components/previews/core/previews_black_list.h
+++ b/components/previews/core/previews_black_list.h
@@ -9,20 +9,21 @@
 
 #include <memory>
 #include <queue>
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
+#include "components/previews/core/previews_experiments.h"
 #include "components/previews/core/previews_opt_out_store.h"
 
 class GURL;
 
 namespace base {
 class Clock;
 }
 
 namespace previews {
 class PreviewsBlackListItem;