Persist offline page info in a navigation entry if needed

components/sessions/content/content_serialized_navigation_driver.h

Index: components/sessions/content/content_serialized_navigation_driver.h
diff --git a/components/sessions/content/content_serialized_navigation_driver.h b/components/sessions/content/content_serialized_navigation_driver.h
index c0911d70e87bd0f102fc689703f557e2349bb382..a471738f33930721bcfc8720ee7899f51e16b79a 100644
--- a/components/sessions/content/content_serialized_navigation_driver.h
+++ b/components/sessions/content/content_serialized_navigation_driver.h
@@ -7,6 +7,12 @@
 
 #include "components/sessions/core/serialized_navigation_driver.h"
 
+#include <map>
+#include <memory>
+#include <string>
+
+#include "base/macros.h"
+#include "components/sessions/content/extended_info_handler.h"
 #include "components/sessions/core/sessions_export.h"
 
 namespace base {
@@ -38,9 +44,27 @@ class SESSIONS_EXPORT ContentSerializedNavigationDriver
   std::string StripReferrerFromPageState(
       const std::string& page_state) const override;
 
+  // Registers a handler that is used to read and write the extended
+  // info stored in SerializedNavigationEntry. As part of serialization |key|
+  // is written to disk, as such once a handler is registered it should always
+  // be registered to the same key.
+  void RegisterExtendedInfoHandler(
+      const std::string& key,
+      std::unique_ptr<ExtendedInfoHandler> handler);
+
+  using ExtendedInfoHandlerMap =
+      std::map<std::string, std::unique_ptr<ExtendedInfoHandler>>;
+
+  // Returns all the registered handlers to deal with the extended info.
+  const ExtendedInfoHandlerMap& GetAllExtendedInfoHandlers() const;
+
  private:
   ContentSerializedNavigationDriver();
   friend struct base::DefaultSingletonTraits<ContentSerializedNavigationDriver>;
+
+  ExtendedInfoHandlerMap extended_info_handler_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(ContentSerializedNavigationDriver);
 };
 
 }  // namespace sessions