ChromeOS: Add RenameCryptohome and migration code.

chromeos/cryptohome/mock_homedir_methods.h

Index: chromeos/cryptohome/mock_homedir_methods.h
diff --git a/chromeos/cryptohome/mock_homedir_methods.h b/chromeos/cryptohome/mock_homedir_methods.h
index 81a82a2b903d46d8a30b89c6702234c9d3856446..b2e5e8a3a1d0f5e4c495d71cfce56dbb8df8099e 100644
--- a/chromeos/cryptohome/mock_homedir_methods.h
+++ b/chromeos/cryptohome/mock_homedir_methods.h
@@ -51,6 +51,10 @@ class CHROMEOS_EXPORT MockHomedirMethods : public HomedirMethods {
                     const KeyDefinition& key,
                     const std::string& signature,
                     const Callback& callback));
+  MOCK_METHOD3(RenameCryptohome,
+               void(const Identification& id_from,
+                    const Identification& id_to,
+                    const Callback& callback));
 
  private:
   bool success_;