Persist offline page info in a navigation entry if needed

components/sessions/core/serialized_navigation_entry.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_SESSIONS_CORE_SERIALIZED_NAVIGATION_ENTRY_H_
 #define COMPONENTS_SESSIONS_CORE_SERIALIZED_NAVIGATION_ENTRY_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 105 matching lines @@
 
   std::set<std::string> content_pack_categories() const {
     return content_pack_categories_;
   }
   void set_content_pack_categories(
       const std::set<std::string>& content_pack_categories) {
     content_pack_categories_ = content_pack_categories;
   }
   const std::vector<GURL>& redirect_chain() const { return redirect_chain_; }
 
+  // Defines the custom behavior to load the offline page if it exists. This is
+  // extracted from the extra request header "X-Chrome-offline" whose value is
+  // a comma/space separated name-value pair.
+  const std::string& offline_page_info() const { return offline_page_info_; }

[sky, 2016/09/13 01:53:31]

Why do we want to persist this as a string rather than something more
meaningful? Enum for example?

[jianli, 2016/09/13 20:29:18]

We have more than one properties needed to persist, like reason and id. In the
future, we might want to add some more properties.

[sky, 2016/09/13 23:30:42]

The down side of a string is that it's easy to miss an incompatible change and
not realize the effects that may have. A real structure/enum is easier to see
changes in and realize what the effects may be.

[jianli, 2016/09/13 23:44:16]

How do we want to persist the struct? Do we still want to serialize the struct
into a string and then persist it? 

I can move OfflinePageHeader struct out of offline_page_request_job.cc and use
it here. But I still need to build OfflinePageHeader struct from extra request
header in ContentSerializedNavigationBuilder::FromNavigationEntry.

+
  private:
   friend class ContentSerializedNavigationBuilder;
   friend class ContentSerializedNavigationDriver;
   friend class SerializedNavigationEntryTestHelper;
   friend class IOSSerializedNavigationBuilder;
   friend class IOSSerializedNavigationDriver;
 
   // Index in the NavigationController.
   int index_;
 
   // Member variables corresponding to NavigationEntry fields.
   int unique_id_;
   GURL referrer_url_;
   int referrer_policy_;
   GURL virtual_url_;
   base::string16 title_;
   std::string encoded_page_state_;
   ui::PageTransition transition_type_;
   bool has_post_data_;
   int64_t post_id_;
   GURL original_request_url_;
   bool is_overriding_user_agent_;
   base::Time timestamp_;
   base::string16 search_terms_;
   GURL favicon_url_;
   int http_status_code_;
   bool is_restored_;    // Not persisted.
   std::vector<GURL> redirect_chain_;  // Not persisted.
+  std::string offline_page_info_;  // Not synced.
 
   // Additional information.
   BlockedState blocked_state_;
   PasswordState password_state_;
   std::set<std::string> content_pack_categories_;
 };
 
 }  // namespace sessions
 
 #endif  // COMPONENTS_SESSIONS_CORE_SERIALIZED_NAVIGATION_ENTRY_H_