ChromeOS cryptohome should be able to use gaia id as user identifier.

chromeos/dbus/fake_cryptohome_client.h

Index: chromeos/dbus/fake_cryptohome_client.h
diff --git a/chromeos/dbus/fake_cryptohome_client.h b/chromeos/dbus/fake_cryptohome_client.h
index 801faafedb1db476d509a390bd011ec33ddde5ce..b5f0a02a864d15174a5bd38feb05fe3018f5ae23 100644
--- a/chromeos/dbus/fake_cryptohome_client.h
+++ b/chromeos/dbus/fake_cryptohome_client.h
@@ -38,6 +38,9 @@ class CHROMEOS_EXPORT FakeCryptohomeClient : public CryptohomeClient {
                        const AsyncMethodCallback& callback) override;
   void AsyncRemove(const std::string& username,
                    const AsyncMethodCallback& callback) override;
+  void RenameCryptohome(const cryptohome::AccountIdentifier& id_from,
+                        const cryptohome::AccountIdentifier& id_to,
+                        const ProtobufMethodCallback& callback) override;
   void GetSystemSalt(const GetSystemSaltCallback& callback) override;
   void GetSanitizedUsername(const std::string& username,
                             const StringDBusMethodCallback& callback) override;
@@ -70,7 +73,7 @@ class CHROMEOS_EXPORT FakeCryptohomeClient : public CryptohomeClient {
   void Pkcs11GetTpmTokenInfo(
       const Pkcs11GetTpmTokenInfoCallback& callback) override;
   void Pkcs11GetTpmTokenInfoForUser(
-      const std::string& username,
+      const std::string& user_id,
       const Pkcs11GetTpmTokenInfoCallback& callback) override;
   bool InstallAttributesGet(const std::string& name,
                             std::vector<uint8_t>* value,