On NSS, treat non-permanent RSA private keys as ephemeral

When generating/using a crypto::RSAPrivateKey with NSS,
prefer the internal software slot over other modules (such as
any TPMs [ChromeOS] or smart cards [Linux]) if the key being
generated is not marked as a permanent key.

BUG=none
R=wtc

Review URL: https://chromiumcodereview.appspot.com/17447009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@207853 0039d316-1c4b-4281-b951-d872f2087c98

crypto/rsa_private_key_nss.cc

@@ -206,7 +206,8 @@ RSAPrivateKey* RSAPrivateKey::CreateWithParams(uint16 num_bits,
 
   scoped_ptr<RSAPrivateKey> result(new RSAPrivateKey);
 
-  ScopedPK11Slot slot(GetPrivateNSSKeySlot());
+  ScopedPK11Slot slot(permanent ? GetPrivateNSSKeySlot() :
+                      PK11_GetInternalSlot());
   if (!slot.get())
     return NULL;
 
@@ -236,7 +237,8 @@ RSAPrivateKey* RSAPrivateKey::CreateFromPrivateKeyInfoWithParams(
 
   scoped_ptr<RSAPrivateKey> result(new RSAPrivateKey);
 
-  ScopedPK11Slot slot(GetPrivateNSSKeySlot());
+  ScopedPK11Slot slot(permanent ? GetPrivateNSSKeySlot() :
+                      PK11_GetInternalSlot());
   if (!slot.get())
     return NULL;