Enable system NSS key slot.

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
index 156504787f21dfe94c199fe110a73bc61758235d..ac3b72c4ce0bd1f4b7940c40aba78d52fcb25019 100644
--- a/crypto/scoped_test_system_nss_key_slot.h
+++ b/crypto/scoped_test_system_nss_key_slot.h
@@ -9,17 +9,20 @@
 #include "base/memory/scoped_ptr.h"
 #include "crypto/crypto_export.h"
 
+// Forward declaration, from <pk11pub.h>
+typedef struct PK11SlotInfoStr PK11SlotInfo;
+
 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.
+// tests to fake the system token that is usually provided by the Chaps module.
+// |slot| is exposed through |GetSystemNSSKeySlot| and |IsTPMTokenReady| will
+// return true.
+// |InitializeTPMTokenAndSystemSlot|, which triggers the TPM initialization,
+// does not have to be called if this helper is used.
 // At most one instance of this helper must be used at a time.
 class CRYPTO_EXPORT_PRIVATE ScopedTestSystemNSSKeySlot {
  public:
@@ -27,6 +30,7 @@ class CRYPTO_EXPORT_PRIVATE ScopedTestSystemNSSKeySlot {
   ~ScopedTestSystemNSSKeySlot();
 
   bool ConstructedSuccessfully() const;
+  PK11SlotInfo* slot() const;
 
  private:
   scoped_ptr<ScopedTestNSSDB> test_db_;