Persist offline page info in a navigation entry if needed

components/sessions/core/serialized_navigation_driver.h

Index: components/sessions/core/serialized_navigation_driver.h
diff --git a/components/sessions/core/serialized_navigation_driver.h b/components/sessions/core/serialized_navigation_driver.h
index 5fc261e4a95c5915f0c3dc2fef55beb33ad14352..c4e6ea6a646e63ccbb62f3a1650c4d5d8e05ce3c 100644
--- a/components/sessions/core/serialized_navigation_driver.h
+++ b/components/sessions/core/serialized_navigation_driver.h
@@ -5,12 +5,19 @@
 #ifndef COMPONENTS_SESSIONS_CORE_SERIALIZED_NAVIGATION_DRIVER_H_
 #define COMPONENTS_SESSIONS_CORE_SERIALIZED_NAVIGATION_DRIVER_H_
 
+#include <map>
+#include <memory>
 #include <string>
 
 #include "components/sessions/core/sessions_export.h"
 
+namespace content {
+class NavigationEntry;
+}
+
 namespace sessions {
 
+class ExtendedInfoHandler;
 class SerializedNavigationEntry;
 
 // The SerializedNavigationDriver interface allows SerializedNavigationEntry to
@@ -50,6 +57,18 @@ class SESSIONS_EXPORT SerializedNavigationDriver {
   // Removes the referrer from the encoded page state.
   virtual std::string StripReferrerFromPageState(
       const std::string& page_state) const = 0;
+
+  // Registers a handler that is used to read and write the extended
+  // info stored in SerializedNavigationEntry.
+  virtual void RegisterExtendedInfoHandler(

[sky, 2016/09/28 00:22:00]

Can you clarify why you want to add these functions here? The functionality is
content specific and should only be in the content side of things. Unless I'm
missing something you should *not* change this code at all, all your changes
should be in components/sessions/content. These functions should be non-virtual
on ContentSerializedNavigationDriver.

+      const std::string& key,
+      std::unique_ptr<ExtendedInfoHandler> handler) = 0;
+
+  using ExtendedInfoHandlerMap =
+      std::map<std::string, std::unique_ptr<ExtendedInfoHandler>>;
+
+  // Returns all the registered handlers to deal with the extended info.
+  virtual const ExtendedInfoHandlerMap& GetAllExtendedInfoHandlers() const = 0;
 };
 
 }  // namespace sessions