[login_manager] Fix race condition that caused ownership to never work

nss_util.h

 // Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef LOGIN_MANAGER_NSS_UTIL_H_
 #define LOGIN_MANAGER_NSS_UTIL_H_
 
 #include <base/basictypes.h>
 #include <string>
 #include <vector>
@@ skipping 24 matching lines @@
 #if defined(UNIT_TEST)
   static void set_factory(Factory* factory) { factory_ = factory; }
 #endif
 
   // Creates an NssUtil, ownership returns to the caller. If there is no
   // Factory (the default) this creates and returns a new NssUtil.
   static NssUtil* Create();
 
   static void BlobFromBuffer(const std::string& buf, std::vector<uint8>* out);
 
+  virtual bool MightHaveKeys() = 0;
+
   virtual bool OpenUserDB() = 0;
 
   // Caller takes ownership of returned key.
   virtual base::RSAPrivateKey* GetPrivateKey(
       const std::vector<uint8>& public_key_der) = 0;
 
   // Caller takes ownership of returned key.
   virtual base::RSAPrivateKey* GenerateKeyPair() = 0;
 
   virtual FilePath GetOwnerKeyFilePath() = 0;
 
   virtual bool Verify(const uint8* algorithm, int algorithm_len,
                       const uint8* signature, int signature_len,
                       const uint8* data, int data_len,
                       const uint8* public_key, int public_key_len) = 0;
 
   virtual bool Sign(const uint8* data, int data_len,
                     std::vector<uint8>* OUT_signature,
                     base::RSAPrivateKey* key) = 0;
 
  private:
   static Factory* factory_;
   DISALLOW_COPY_AND_ASSIGN(NssUtil);
 };
 }  // namespace login_manager
 
 #endif  // LOGIN_MANAGER_NSS_UTIL_H_