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..4af08fb75f1d083424a940f475dfc326de0a2656 100644
--- a/components/sessions/core/serialized_navigation_driver.h
+++ b/components/sessions/core/serialized_navigation_driver.h
@@ -5,10 +5,15 @@
 #ifndef COMPONENTS_SESSIONS_CORE_SERIALIZED_NAVIGATION_DRIVER_H_
 #define COMPONENTS_SESSIONS_CORE_SERIALIZED_NAVIGATION_DRIVER_H_
 
+#include <map>
 #include <string>
 
 #include "components/sessions/core/sessions_export.h"
 
+namespace content {
+class NavigationEntry;
+}
+
 namespace sessions {
 
 class SerializedNavigationEntry;
@@ -18,6 +23,24 @@ class SerializedNavigationEntry;
 // must be provided by the driver on each platform.
 class SESSIONS_EXPORT SerializedNavigationDriver {

[sky, 2016/09/27 22:30:27]

This code can't depend upon content. Your changes should be in the content side
only.

[jianli, 2016/09/27 23:30:32]

Done.

  public:
+  // The interface that handles how the extended info is converted betweened the

[sky, 2016/09/27 22:30:27]

How about:
This interface is used to store and retrieve arbitrary key/value pairs for a
NavigationEntry that are not a core part of NavigationEntry. WARNING:
implementations must deal with versioning. In particular RestoreExtendedInfo()
may be called with data from a previous version of Chrome.

[jianli, 2016/09/27 23:30:32]

Done.

+  // one stored in SerializedNavigationEntry and the one used in
+  // NavigationEntry.
+  class SESSIONS_EXPORT ExtendedInfoHandler {

[sky, 2016/09/27 22:30:27]

Move this into it's own header.

[jianli, 2016/09/27 23:30:32]

Done.

+   public:
+    virtual ~ExtendedInfoHandler() {}
+
+    // Returns the extended info from NavigationEntry for
+    // SerializedNavigationEntry to save it.
+    virtual std::string GetExtendedInfo(
+        const content::NavigationEntry& entry) const = 0;
+
+    // Puts the extended info, extracted from SerializedNavigationEntry, into
+    // NavigationEntry.
+    virtual void RestoreExtendedInfo(
+        const std::string& info, content::NavigationEntry* entry) = 0;
+  };
+
   virtual ~SerializedNavigationDriver() {}
 
   // Returns the singleton SerializedNavigationDriver.
@@ -50,6 +73,18 @@ 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 could be used to read and write the extended

[sky, 2016/09/27 22:30:27]

'could be' -> is 

[jianli, 2016/09/27 23:30:32]

Done.

+  // info stored in SerializedNavigationEntry.
+  virtual void RegisterExtendedInfoHandler(
+      const std::string& key,
+      std::unique_ptr<ExtendedInfoHandler> handler) = 0;
+
+  typedef std::map<std::string, std::unique_ptr<ExtendedInfoHandler>>

[sky, 2016/09/27 22:30:27]

using.

[jianli, 2016/09/27 23:30:32]

Done.

+      ExtendedInfoHandlerMap;
+
+  // Returns all the registered handlers to deal with the extended info.
+  virtual const ExtendedInfoHandlerMap& GetAllExtendedInfoHandlers() const = 0;
 };
 
 }  // namespace sessions