Make session restore understand that tabs have multiple SessionStorageNamespaces.

chrome/browser/sessions/session_types.h

Index: chrome/browser/sessions/session_types.h
diff --git a/chrome/browser/sessions/session_types.h b/chrome/browser/sessions/session_types.h
index 0c3335b358f2ee251b6765b32b4c22c3b3793286..b2d8e54de65b1f8340841b2996014aabec5572b4 100644
--- a/chrome/browser/sessions/session_types.h
+++ b/chrome/browser/sessions/session_types.h
@@ -5,6 +5,7 @@
 #ifndef CHROME_BROWSER_SESSIONS_SESSION_TYPES_H_
 #define CHROME_BROWSER_SESSIONS_SESSION_TYPES_H_
 
+#include <map>
 #include <string>
 #include <vector>
 
@@ -180,8 +181,8 @@ struct SessionTab {
 
   std::vector<TabNavigation> navigations;
 
-  // For reassociating sessionStorage.
-  std::string session_storage_persistent_id;
+  // Maps the storage partition id to its session storage persistent id.
+  std::map<std::string, std::string> session_storage_persistent_id_map;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SessionTab);