Create and store persistent unique ids for sessionStorage.

content/public/browser/session_storage_namespace.h

Index: content/public/browser/session_storage_namespace.h
diff --git a/content/public/browser/session_storage_namespace.h b/content/public/browser/session_storage_namespace.h
index 5b17d0ceaebd56e8c45794931e5525c6d17d47f8..4b950e101f08483478b8e59a5da903bbda3562db 100644
--- a/content/public/browser/session_storage_namespace.h
+++ b/content/public/browser/session_storage_namespace.h
@@ -6,16 +6,19 @@
 #define CONTENT_PUBLIC_BROWSER_SESSION_STORAGE_NAMESPACE_H_
 #pragma once
 
+#include <string>
+
 #include "base/memory/ref_counted.h"
 
 namespace content {
 
 // This is a ref-counted class that represents a SessionStorageNamespace.
 // On destruction it ensures that the storage namespace is destroyed.
-// NOTE: That if we're shutting down, we don't strictly need to do this, but
-//       it keeps valgrind happy.
 class SessionStorageNamespace
     : public base::RefCountedThreadSafe<SessionStorageNamespace> {
+ public:
+  virtual int64 id() const = 0;

[jochen (gone - plz use gerrit), 2012/06/15 13:57:21]

can you please document these two getters?

also, currently you're not using them outside of content/. Will that change?
Otherwise, the getters should not be on the public interface.

[marja, 2012/06/15 14:31:32]

Added docs: 

// Returns the ID of the |SessionStorageNamespace|. The ID is unique among all
// SessionStorageNamespace objects, but not unique across browser runs.

// Returns the persistent ID for the |SessionStorageNamespace|. The ID is
// unique across browser runs.

They'll be used outside content.

+  virtual const std::string& persistent_id() const = 0;
  protected:

[jochen (gone - plz use gerrit), 2012/06/15 13:57:21]

empty line before protected

[marja, 2012/06/15 14:31:32]

Done.

   friend class base::RefCountedThreadSafe<SessionStorageNamespace>;
   virtual ~SessionStorageNamespace() {}