[Sync] Introduce SyncedSessionWindow type.

ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions.mm

Index: ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions.mm
diff --git a/ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions.mm b/ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions.mm
index 3d96d44fb520f6f934fd24eebd2b113f7ce86d00..42cc6123e032dc11caa77ea6e91da45f841e1f43 100644
--- a/ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions.mm
+++ b/ios/chrome/browser/ui/ntp/recent_tabs/synced_sessions.mm
@@ -106,7 +106,7 @@ void DistantSession::InitWithSyncedSession(
   } else {
     // Order tabs by their visual position within window.
     for (const auto& kv : synced_session->windows) {
-      for (const auto& session_tab : kv.second->tabs) {
+      for (const auto& session_tab : kv.second->wrapped_window.tabs) {
         AddTabToDistantSession(*session_tab, synced_session->session_tag, this);
       }
     }