Adding a short blacklist period after every previews opt out

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 2bfe91e31aec109edc12cb7f126e40fe0109f92e..a1e36cc9033a2eb1b403f9cc71dee1e72a1e3508 100644
--- a/components/previews/core/previews_black_list.h
+++ b/components/previews/core/previews_black_list.h
@@ -8,21 +8,23 @@
 #include <stdint.h>
 
 #include <memory>
 #include <queue>
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/optional.h"
 #include "base/threading/thread_checker.h"
+#include "base/time/time.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 {
@@ -97,20 +99,23 @@ class PreviewsBlackList {
   // Enqueues a task to run when when loading black list information has
   // completed. Maintains the order that tasks were called in.
   void QueuePendingTask(base::Closure callback);
 
   // Map maintaining the in-memory black list.
   std::unique_ptr<BlackListItemMap> black_list_item_map_;
 
   // Whether the black list is done being loaded from the backing store.
   bool loaded_;
 
+  // The time of the last opt out for this session.
+  base::Optional<base::Time> last_opt_out_time_;
+
   // The backing store of the black list information.
   std::unique_ptr<PreviewsOptOutStore> opt_out_store_;
 
   // Callbacks to be run after loading information from the backing store has
   // completed.
   std::queue<base::Closure> pending_callbacks_;
 
   std::unique_ptr<base::Clock> clock_;
 
   base::ThreadChecker thread_checker_;