Extract ScopedTestNSSDB from nss_util.

crypto/scoped_test_system_nss_key_slot.h

Index: crypto/scoped_test_system_nss_key_slot.h
diff --git a/crypto/scoped_test_system_nss_key_slot.h b/crypto/scoped_test_system_nss_key_slot.h
new file mode 100644
index 0000000000000000000000000000000000000000..156504787f21dfe94c199fe110a73bc61758235d
--- /dev/null
+++ b/crypto/scoped_test_system_nss_key_slot.h
@@ -0,0 +1,39 @@
+// Copyright 2014 The Chromium 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 CRYPTO_SCOPED_TEST_SYSTEM_NSS_KEY_SLOT_H_
+#define CRYPTO_SCOPED_TEST_SYSTEM_NSS_KEY_SLOT_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "crypto/crypto_export.h"
+
+namespace crypto {
+
+class ScopedTestNSSDB;
+
+// Opens a persistent NSS software database in a temporary directory and sets
+// the test system slot to the opened database. This helper should be created in
+// tests where no system token is provided by the Chaps module and before
+// InitializeTPMTokenAndSystemSlot is called. Then the opened test database will
+// be used and the initialization continues as if Chaps had provided this test
+// database. In particular, the DB will be exposed by |GetSystemNSSKeySlot| and
+// |IsTPMTokenReady| will return true.
+// At most one instance of this helper must be used at a time.
+class CRYPTO_EXPORT_PRIVATE ScopedTestSystemNSSKeySlot {
+ public:
+  explicit ScopedTestSystemNSSKeySlot();
+  ~ScopedTestSystemNSSKeySlot();
+
+  bool ConstructedSuccessfully() const;
+
+ private:
+  scoped_ptr<ScopedTestNSSDB> test_db_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedTestSystemNSSKeySlot);
+};
+
+}  // namespace crypto
+
+#endif  // CRYPTO_SCOPED_TEST_SYSTEM_NSS_KEY_SLOT_H_