[Sync] Add per-navigation timestamps/unique ids to tab sync.

chrome/browser/sync/glue/synced_session.h

Index: chrome/browser/sync/glue/synced_session.h
diff --git a/chrome/browser/sync/glue/synced_session.h b/chrome/browser/sync/glue/synced_session.h
index c87cc282a8cab5627a10f29e05e6fefe9c3656f9..b886a55dcf0fdc766e5a1421b11f326d8b6ad517 100644
--- a/chrome/browser/sync/glue/synced_session.h
+++ b/chrome/browser/sync/glue/synced_session.h
@@ -11,12 +11,54 @@
 
 #include "base/time.h"
 #include "chrome/browser/sessions/session_id.h"
+#include "chrome/browser/sessions/session_types.h"
 
-struct SessionTab;
-struct SessionWindow;
+namespace content {
+class NavigationEntry;
+}
 
 namespace browser_sync {
 
+// Sync-specific wrapper around a normal TabNavigation.
+// Copy semantics supported.
+class SyncedTabNavigation : public TabNavigation {
+ public:
+  SyncedTabNavigation();
+  SyncedTabNavigation(const SyncedTabNavigation& tab);
+  SyncedTabNavigation(int index,
+                      const GURL& virtual_url,
+                      const content::Referrer& referrer,
+                      const string16& title,
+                      const std::string& state,
+                      content::PageTransition transition,
+                      int unique_id,
+                      const base::Time& timestamp);
+  virtual ~SyncedTabNavigation();
+
+  // Unique id for this navigation.
+  void set_unique_id(int unique_id);
+  int unique_id() const;
+
+  // Timestamp this navigation occurred.
+  void set_timestamp(const base::Time& timestamp);
+  base::Time timestamp() const;
+
+ private:
+  int unique_id_;
+  base::Time timestamp_;
+};
+
+// Sync-specific wrapper around a normal SessionTab to support using
+// SyncedTabNavigation.
+struct SyncedSessionTab : public SessionTab {
+ public:
+  SyncedSessionTab();
+  ~SyncedSessionTab();
+
+
+  std::vector<SyncedTabNavigation> synced_tab_navigations;
+};
+
 // Defines a synced session for use by session sync. A synced session is a
 // list of windows along with a unique session identifer (tag) and meta-data
 // about the device being synced.