Showing previews UI for Offline Previews

components/offline_pages/request_header/offline_page_header.h

Index: components/offline_pages/request_header/offline_page_header.h
diff --git a/components/offline_pages/request_header/offline_page_header.h b/components/offline_pages/request_header/offline_page_header.h
index 370fe667817795d3d694b8cb2cd28e85b28a02c0..84dedd7173ce136f78d83f7ee27f7b8ced9bff9f 100644
--- a/components/offline_pages/request_header/offline_page_header.h
+++ b/components/offline_pages/request_header/offline_page_header.h
@@ -47,20 +47,23 @@ struct OfflinePageHeader {
     DOWNLOAD,
     RELOAD
   };
 
   OfflinePageHeader();
 
   // Constructed from a request header value string.
   // The struct members will be cleared if the parsing failed.
   explicit OfflinePageHeader(const std::string& header_value);
 
+  // Creates a copy of |other|.
+  OfflinePageHeader(const OfflinePageHeader& other);
+
   ~OfflinePageHeader();
 
   // Returns the full header string, including both key and value, that could be
   // passed to set extra request header.
   std::string GetCompleteHeaderString() const;
 
   void Clear();
 
   // Set if failed to parse a request header value string. For testing only.
   bool did_fail_parsing_for_test;